Loading...
The URL can be used to link to this page
Your browser does not support the video tag.
Home
My WebLink
About
agenda.council.worksession.20240415
AGENDA CITY COUNCIL WORK SESSION April 15, 2024 4:00 PM, City Council Chambers 427 Rio Grande Place, Aspen I.Work Session I.A Castle Creek Bridge and Entrance to Aspen Zoom Meeting Instructions Join from a PC, Mac, iPad, iPhone or Android device: Please click this URL to join: https://us06web.zoom.us/j/87316011300? pwd=kIjWoNkLel6yoNe9cBcd2ODsBerQkO.1 Passcode: 81611 Or join by phone: Dial: US: +1 346 248 7799 Webinar ID: 873 1601 1300 Passcode: 81611 International numbers available: https://us06web.zoom.us/u/kb0B4rfzRH 2024 3-24 Castle Creek Bridge Work Session MemoPete.docx Appendix A Feasibility Assessment.pdf Appendix B City of Aspen_SCurve Memo.pdf Appendix C CCB_NEPAProcessOptions.pdf 1 1 MEMORANDUM TO:Mayor and Council FROM:Jenn Ooton, Senior Project Manager Pete Rice, PE, Director of Transportation and Parking Lynn Rumbaugh, Mobility Division Manager Carly McGowan, PE, Senior Project Manager THROUGH:Sara Ott, City Manager Scott Miller, Public Works Director Tyler Christoff, PE, Deputy Public Works Director DATE OF MEMO:April 8th, 2024 MEETING DATE:April 15th, 2024 RE:Castle Creek Bridge Evaluation REQUEST OF COUNCIL: This is a work session to review the results of the Jacobs Engineering review of the existing bridge, understanding of the National Environmental Policy Act (NEPA), and conceptual design of S-Curve softening. SUMMARY AND BACKGROUND: Following a 70-day community awareness effort in late 2022 and early 2023 designed to share information to increase understanding of the history of the Entrance to Aspen, to create clarity around the Preferred Alternative and the existing Record of Decision, Council approved a contract to answer questions related to the existing bridge based on community feedback and questions during the awareness process. Council directed staff to focus on the following three area: 1. Understanding National Environmental Policy Act (NEPA) requirements and implications of departing from the Preferred Alternative and; 2. Exploring with conceptual design how the S Curves could be softened to improve traffic flow exiting town; and 3. Understanding impacts of rehabilitating the existing bridge or re-building the bridge in its existing alignment including cost, construction duration, and community impacts. This work included both a Colorado Department of Transportation-style bridge evaluation report and a hands on inspection of the bridge. 2 A BRIEF HISTORY OF THE ENTRANCE TO ASPEN 1990’s Problems with growth, air quality, traffic and congestion 1993 Citizens and elected officials met numerous times and developed the AACP 1993 Paid parking was implemented 1995 Community, elected officials, Colorado Department of Transportation (CDOT), Federal Highway Association (FHWA) to develop Project Need & Intent and 10 project objectives 1995 Draft Environmental Impact Statement (DEIS) 1996 Draft Supplemental Environmental Impact Statement (DSEIS) 1997 Final Environmental Impact Statement (FEIS) 1998 Record of Decision (ROD) 2007 Reevaluation of Record of Decision 1975-2002 26 votes 1998 RECORD OF DECISION PROJECT NEED The capacity of the existing transportation system is insufficient during peak periods. Safety, clean air, the visitor’s experience, and resident’s quality of life are compromised. 1998 RECORD OF DECISION INTENT To provide a balanced, integrated transportation system for residents, visitors and commuters that reduces congestion and pollution by reducing and/or managing the number of vehicles on the road system. The system should reflect the character and scale of the Aspen Community. Through a process responsive to community-based planning, the EIS shall identify, analyze, select and implement the best transportation alternative for the short- and long- term goals of the community compatibility, safety, environmental preservation, clean air, quality of life, and transportation capacity. The alternative chosen during the EIS process in the late 1990s was evaluated to be consistent with the Aspen/Snowmass/Pitkin County goal of limiting vehicles in 2015 to levels at or below those of 1994. 10 PROJECT OBJECTIVES In 1995 elected officials from Aspen, Pitkin County and Snowmass and representatives from CDOT, FHWA a technical advisory committee and citizens developed the ten project objectives that the project must meet. All alternatives would be screened against these ten project objectives as well as the project need and intent. The project need, intent and project objectives were the foundation on which the decisions for the FEIS and ROD were made, and other solutions were measured against. 1. Community Based Planning 2. Transportation Capacity 3 3. Safety 4. Environmentally Sound Alternative 5. Community Acceptability 6. Financial Limitations 7. Clean Air Act Requirements 8. Emergency Access 9. Livable Communities 10.Phasing THE PREFERRED ALTERNATIVE (PA) The Preferred Alternative came from a screening and selection process as part of the FEIS. Over 43 different alternatives were reviewed and compared to the project need and intent and the ten project objectives. The alternatives were screened from consideration through a reality check, fatal flaw, and comparative, for potential alignment, traffic lane alignment, profile and travel mode options. The Preferred Alternative is a combination of highway and intersection improvements, a transit system, and an incremental transportation management ™ program. The highway component will consist of a two-lane parkway that generally follows the existing alignment, except at the Maroon Creek crossing and across the Marolt-Thomas Property. The transit component includes a LRT system, that if local support and/or funding are not available will be developed initially as exclusive bus lanes. The PA is a variation of the Modified Direct Alternative evaluated in the DSEIS from 1996. Why was the Preferred Alternative “preferred?” CDOT and FHWA have chosen the PA because it best meets the local communities needs and desires, fulfills the project objectives, and provides flexibility in future designs. Meets project need and intent and 10 project objectives Provides capacity for forecasted person trips, but limit vehicle trips Reduces accident rate on “S” curves, Provides alternate route for emergency vehicles Minimizes negative impacts on the environment, open space, and historic & recreational resources Reflects character and scale of Aspen Aesthetically acceptable solution Allows for future transit options and upgrades DISCUSSION: 4 Jacobs Engineering independently evaluated the existing Castle Creek Bridge during the last week of November to help identify critical issues that the community and Council requested in 2023. The consulting team is evaluating the feasibility of either rehabilitating or replacing the State Highway 82 (SH 82) bridge over Castle Creek and Power Plant Road. The information is included as Appendix A The Castle Creek Bridge Feasibility Assessment. Castle Creek Bridge Feasibility Study Existing Bridge Assessment Details - Inspections of the 63-year-old bridge have identified several issues, including signs of wear and major deterioration and corrosion of structural steel and concrete bridge components. A bridge's sufficiency rating is a comprehensive assessment that considers factors such as structural condition, load rating, traffic data, and public importance. The rating is calculated using a formula outlined by the Federal Highway Administration and reflects the bridge's ability to remain in service and compares the existing bridge to a new one meeting current engineering standards. The assessment for Castle Creek Bridge has designated the bridge as functionally obsolete, meaning the deck geometry, load-carrying capacity, clearance, or approach roadway alignment no longer meet the current standards for the highway system of which the bridge is an integral part. The sufficiency rating also considers the load rating of the bridge structure. All structures require a load rating defining their long term high frequency live load (traffic) capacity. The NBI rating for the Castle Creek Bridge structure is 24.6 tons. The minimum inventory load rating goal for any structure on a state highway is 36 tons. Each element of a bridge is coded during a bridge inspection, from 0 to 9 based on their condition state within NBI Standards. The code is dependent upon the defect location, frequency, and condition. The ratings from the inspection are included below: Superstructure and substructure condition code history of the bridge based on the NBI database (NBI 2024). During a 2009 inspection, (CDOT 2009) a decline in the superstructure condition code to 3 (“Poor”) was noted, necessitating immediate attention. According to CDOT records, extensive repairs and rehabilitation efforts were implemented on the bridge in 2011 to improve the condition code of the bridge. Despite 5 these substantial rehabilitation efforts, they were only sufficient to elevate the superstructure to a ”Fair” code. The inspection has indicated that deck repairs may be warranted once again. The exterior girders are also in need of replacement, which could coincide with the deck repairs. The underside of the concrete deck exhibits signs of degradation and widespread surface cracking, and the steel girders show varying degrees of corrosion, with exterior girders displaying considerable corrosion and sag. Numerous tack welds and girder stiffeners exhibit cracks, and protective coatings on steel elements have failed, contributing to accelerated corrosion. To preserve the life of the bearings and abutments, the expansion joints should be replaced. The bearings at the abutments need to be replaced, and bearings at the piers need additional rehab. Inadequate joint sealing at Abutment 6 raises concerns about the bridge’s structural performance, and notable movement of the bridge was observed through the existing conditions of the bearings. The bridge’s concrete substructure shows significant signs of deterioration and in several locations requires immediate attention to prevent further overall damage or load carrying capacity. Rehabilitation Option Given the considerable deterioration of bridge components, a comprehensive rehabilitation plan is essential and would include bearing replacement, exterior girder replacement (requiring sidewalk replacement), protective steel coating rehabilitation, tack weld removal and monitoring, concrete deck repairs and asphalt overlay, pier cap repairs, joint seal replacement, and bridge rail replacement. Regular monitoring and inspections would be crucial to evaluate the effectiveness of the rehabilitation measures and to promptly address issues as they emerge. The rehabilitation measures would address the bridge’s immediate maintenance needs, prevent further deterioration, and maintain its structural integrity and safety while improving the bridge’s long-term durability. Rehabilitation would not raise the load rating of the bridge to current standards, reduce maintenance needs, or address the limited functionality of the narrow roadway width. The rating after rehabilitation would still be considered functionally obsolete. The rehabilitation measures would not substantially improve the bridge’s condition to a level where total replacement would not be deemed necessary. The rehabilitation process would occur in two phases each lasting approximately 6 months each. The project duration would be done in two years dictated by area weather conditions. The approximate cost for the work is $44,000,000. Replacement of Castle Creek Bridge 6 Several bridge types were evaluated, including precast concrete, steel, and cast-in-place concrete bridges. The steep terrain and facilities under the bridge limit the space for large cranes, eliminating the ability to use precast concrete. Crane placement for steel requires closures of Power Plant Road. Therefore, only cast-in-place concrete is considered feasible because it provides the best constructability and limits impacts to the SH 82 profile. In addition, it was found that a four-span bridge would provide the best opportunity to control span lengths for a shallower structure depth that would accommodate traditional phased construction. Bridge replacement alternatives would be designed to meet current design standards and support heavier vehicle loads. Four alternatives for the bridge replacement have been studied for the work session and outlined in detail in Appendix A. The following replacement alternatives have been studied: 1. Two lane bridge replacement in the same location of the existing bridge. One phasing option for this alternative was considered, because the only other option would be to fully close and replace the existing bridge. Four phases of construction would be required, but a single lane of traffic would be able to remain open during all construction phases while a detour lane would handle the other direction of travel. A temporary travel lane would be built on the bridge for use during construction and would remain in place after construction completion. As such, the width of the new two-lane bridge would be approximately 8 feet wider than the existing bridge. The new bridge would be located within the existing right-of-way limits; therefore, no right-of-way acquisition would be required. The estimated cost is apprxoimately $69,000,000. 2. Three-Lane Centered: Phasing under this option is similar to the two-lane alternative. The main difference is that the bridge segments would be wider to accommodate the width for a third lane. The bridge would be located within the existing right-of-way limits; therefore, no right-of-way acquisition would be required. The estimated cost is approximately $73,000,000. 3. Three-Lane Faster: This option would demolish portions of the existing bridge early in the first phase to allow earlier construction of two temporary lanes, thus limiting the need for a single lane to one phase. However, pedestrians would be rerouted under the bridge in all phases. This option would shift the bridge approximately 3 feet to the south to avoid residences to the north, resulting in right-of-way impacts and removal of nearby trees. However, the south edge of the new bridge would almost be above the residence on Harbour Lane that may require ROW acquisition not included in the cost estimate. Additional care would be required during construction to protect this residence. The approximate cost is $82,000,000 4. Three-Lane Shifted: This option would maintain two lanes on the bridge during all construction phases. Similar to Faster, this option would shift the new bridge to the south to avoid residences to the north, and as a result, the residence on Harbour Lane would nearly be under the bridge. The shift to the south would 7 require rebuilding road segments at both ends of the bridge to align sidewalks. Like Faster, this option would extend outside existing right-of-way, affecting nearby residences and potentially requiring additional right-of-way acquisitions that are not included in the estimate. A variation was considered that would provide pedestrian access during all phases by adding a pedestrian path on the bridge, but this would shift the bridge farther south, placing the bridge over a residence and resulting in right-of-way impacts. Therefore, it would not be feasible to accommodate pedestrians during all phases of this option. The approximate is $69,000,000. The phasing for construction for the Castle Creek Bridge replacement varies on impact to the public based on the method and is discussed in detail in Appendix A and will be presented during the work session. Several accelerated bridge construction (ABC) techniques were analyzed to determine which, if any, would be a good fit for this spatially constrained site. ABC typically reduces onsite construction time and improves site constructability, total project delivery time, and work-zone safety for the traveling public. It can also reduce traffic impacts during construction and weather-related time delays. It was determined that these ABC methods would not be successful for the CCB because of site terrain and space constraints for assembling and operating the large cranes required to move the heavy bridge components into place, larger construction footprint that impedes on ROW or other facilities, and/or lack of a viable detour during an extended closure of SH 82. Considering these issues, traditional bridge construction phasing or a full closure of SH 82 (where the existing bridge is demolished and rebuilt with traffic on a detour) are the only feasible options. S-Curve Modification for Outbound Congestion Improvements The goal for S-curve modification is to decrease the outbound congestion during the peak periods by making infrastructure changes to allow better geometry and reducing the 6 major pinch points indicated in Appendix B. Two options are available but rely on some direction of Castle Creek Bridge. Any of the work within the area of the S-Curves does not impact the Record of Decision and would need to go through a process of approval through CDOT similar to the work that was done in the area in 2018. The benefit to the process is that the improvements can be pursued immediately without impact to Castle Creek Bridge and the Record of Decision. The two options presented for the S-Curves in Appendix B are designed for both scenarios of two or three lane Castle Creek Bridge replacements. The key improvements would include the softening of the curves to improve vehicle movement, creating a transit lanes without merging into general traffic lanes to create additional congestion and creating less access points along 6th, 7th or 8th Streets. These improvements can be made to immediately improve outbound congestion. The conceptual drawings indicate ROW acquisition that will be required and the impact to trees. 8 NEPA and Record of Decision The National Environmental Policy Act sets forth federal requirements to determine the environmental effects of work prior to making decisions. It is the required federal process that was used in the development of the existing Record of Decision for the Entrance to Aspen that was approved in 1998, and that would be used in any process to depart from the existing approvals. The Jacobs Engineering analysis addresses Council’s questions on the implications of pursuing changes to the PA and leaving the legally valid and approved Record of Decision. Appendix C is a table that outlines estimated costs, timelines and information about the type of federal NEPA process required based on the change being considered. 1. Smaller changes to the PA that do not result in significant impact, such as a roundabout slip ramp and the S-Curve softening, would require a re-evaluation. 2. Bridge rehabilitation would require an Environmental Assessment. 3. Consideration of a different alternative to the PA, such as replacing the bridge in place or pursuing an alignment alternative that was fully considered during the original EIS evaluation would require a more in-depth federal process. Replacing the existing bridge in-kind or with three lanes would require a new EIS/ROD. A new EIS process would require new scoping including reassessing the purpose and need and the community goals. FINANCIAL IMPACTS: Staff will submit cost impacts after receiving Council direction. The City of Aspen will be responsible for funding modifications to the existing Record of Decision. ENVIRONMENTAL IMPACTS: For any construction of the Entrance to Aspen project, the project must follow National Environmental Protection Act (NEPA) requirements. The environmental impacts of the Preferred Alternative were heavily examined during the EIS process in the 1990’s. Should the Council choose to deviate from the Preferred Alternative with an alternative solution, the environmental impacts will be required to be studied during a new or supplemental EIS process. The City of Aspen must follow this federal process that involves the greater community’s input in a similar fashion to the 1998 Record of Decision and can not be fully decided by Aspen City Council alone. ALTERNATIVES: 9 A. Understanding the federal EIS and NEPA process will be required prior implementing alternative alignments from the approved Preferred Alternative, the following alternatives would be pursued by staff through a public process with the greater community and is required for the final selection of an alignment: 1. Rehabilitation of the existing Castle Creek Bridge. 2. Two lane replacement of the existing Castle Creek Bridge 3. Three lane centered of the existing Castle Creek Bridge 4. Three lane shifted of the existing Castle Creek Bridge 5. Phasing of construction may include a temporary bridge structure. B. Proceed with a pre-NEPA process prior to leaving the Record of Decision to understand the outcome of the process. This would explore alternative alignments that would be derived through a federal process without leaving the Record of Decision. C. Direct staff to complete a transportation study to explore potential traffic congestion opportunties that can be implemented per Council’s Transportation Goal. D. Direct staff to pursue construction documents for S-Curve improvements or engage in a modeling effort to show the impact on congestion relief the improvements would have on outbound traffic. E. Council can choose not to take action and the bridge rating decreases to a poor condition, CDOT is authorized to implement the Preferred Alternative as described in the 1998 Record of Decision. F. Explore the viability of alignments through the City of Aspen to assure feasibility of implementation. Although the City of Aspen can propose an alignment and the feasibility of implementation, the federal process would be required prior to fully proceeding into construction. Council can pursue the feasibility of alignments to at a conceptual level (similar process to the S-Curves) to understand the impacts prior to modifications to the ROD. G. Direct staff to assess the impact to the community economics and work force based on a traffic model during the reconstruction of the existing Castle Creek Bridge. H. Engage in the community to explore through survey questions the values on the entrance question. QUESTIONS FOR COUNCIL: 1. Does Council want to proceed with construction drawings for the softening of the S-Curves with a goal of increasing capacity wihtout impacting the Record of Decision? 2. Does Council want to proceed with construction drawings for replacement of the bridge in its existing alignment knowing the process would need to go through the federal NEPA process prior to construction? 10 3. Does Council need additional information on the NEPA process, downvalley community support for alternatives, traffic impacts of reconstruction, or economic impacts? Are there any additional questions raised through the Awareness campaign that Council would like to address further? 4. Does Council want to proceed with a pre-NEPA process to explore alternatives other than the Preferred Alternative without leaving the current Record of Decision? 5. Does Council support a regional infromation sharing with partners like RFTA, EOTC and stakeholders to assure transparency in the public prior to pursuing modifications to the Record of Decision? 6. Does Council want to complete a transportation study to explore potential traffic congestion opportunties that can be implemented per Council’s Transportation Goal through the corridor with the limits being Brush Creek Parking Facility and the S-Curves? 7. Does Council want to explore alternatives at a conceptual level in a fashion similar to the S-Curves for alignments outside this scope of work to explore the impacts and understand the process for proceeding beyond the coneptual work? RECOMMENDATION: Staff recommendation could be adjusted based on the Council questions requested above. Staff recommends exploring an alignment selection through a Pre-NEPA process prior to exiting the 1998 Federal Document to assure the outcome is aligned with Council’s vision. Outbound congestion goals can be improved through the direction of S-Curve construction drawing implementation and concentrated studies focus on relieving the conflict points through the corridor. CITY MANAGER COMMENTS: Attachments: Appendix A Castle Creek Bridge Feasibility Study Appendix B S-Curve Technical Memo Appendix C Castle Creek Bridge NEPA Process Memo 11 12 SH 82 Over Castle Creek Bridge Feasibility Study Document No: 240207140925_5d9775bf Version: Draft City of Aspen Structure No. H-09-B Castle Creek Bridge 13 SH 82 Over Castle Creek Bridge Feasibility Study Client Name: City of Aspen Project Name: Castle Creek Bridge Client Reference: Structure No. H-09-B Project No: WXYB4801 Document No: 240207140925_5d9775bf Project Manager: Jim Clarke Version: Draft Prepared by: Beth Tosti, Structures Lead Date: File name: Final_CCB Feasibility Report_r2.docx Jacobs Engineering Group Inc. 6312 S. Fiddlers Green Circle Suite 300N Greenwood Village, CO 80111 United States T +1.720.286.2000 www.jacobs.com © Copyright 2024 Jacobs Engineering Group Inc.. All rights reserved. The content and information contained in this document are the property of the Jacobs group of companies (“Jacobs Group”). Publication, distribution, or reproduction of this document in whole or in part without the written permission of Jacobs Group constitutes an infringement of copyright. Jacobs, the Jacobs logo, and all other Jacobs Group trademarks are the property of Jacobs Group. NOTICE: This document has been prepared exclusively for the use and benefit of Jacobs Group client. Jacobs Group accepts no liability or responsibility for any use or reliance upon this document by any third party. 14 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf i Acronyms and Abbreviations ......................................................................................................................................... vi 1. Executive Summary ............................................................................................................................................... 1 2. Site Description and Design Features ............................................................................................................ 16 2.1 Existing Structure ................................................................................................................................................ 16 2.2 Traffic Detours ..................................................................................................................................................... 17 2.3 Utilities ................................................................................................................................................................... 17 2.4 Geotechnical Summary .................................................................................................................................... 19 2.5 Hydraulic Summary ........................................................................................................................................... 19 2.6 Environmental Concerns .................................................................................................................................. 19 2.7 Roadway Design Features ................................................................................................................................ 21 3. Structural Design Criteria ................................................................................................................................. 21 3.1 Design Specification and Criteria .................................................................................................................. 21 3.2 Loading................................................................................................................................................................... 21 3.3 Aesthetic Requirements ................................................................................................................................... 22 4. Bridge Rehabilitation Feasibility ..................................................................................................................... 22 4.1 Bridge Condition Assessment ......................................................................................................................... 22 4.2 Summary of Field Inspection .......................................................................................................................... 24 4.2.1 Concrete Deck and Asphalt Overlay ................................................................................................ 24 4.2.2 Steel Girders ............................................................................................................................................ 25 4.2.3 Girder Stiffener and Tack Welds ....................................................................................................... 27 4.2.4 Steel Protective Coating ...................................................................................................................... 29 4.2.5 Bearings ..................................................................................................................................................... 30 4.2.6 Diaphragms .............................................................................................................................................. 32 4.2.7 Pier Caps ................................................................................................................................................... 33 4.2.8 Abutments ................................................................................................................................................ 34 4.2.9 Expansion Joints ..................................................................................................................................... 35 4.2.10 Slope Protection ................................................................................................................................. 37 4.3 Rehabilitation Recommendations ................................................................................................................ 37 4.4 Sufficiency Rating Calculation after Proposed Rehabilitation ............................................................ 40 4.5 Construction Phasing ........................................................................................................................................ 40 4.6 Schedule ................................................................................................................................................................ 42 4.7 Cost Estimate ....................................................................................................................................................... 42 4.8 Summary and Conclusions .............................................................................................................................. 42 5. Bridge Replacement Feasibility ...................................................................................................................... 43 5.1 Bridge Width Alternatives ................................................................................................................................ 43 5.2 Structure Type ..................................................................................................................................................... 44 5.2.1 Span Configurations.............................................................................................................................. 44 5.2.2 Materials ................................................................................................................................................... 46 15 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf ii 5.3 Construction Phasing ........................................................................................................................................ 51 5.3.1 Service During Construction ............................................................................................................... 51 5.3.2 Phasing Options ..................................................................................................................................... 53 5.3.3 Schedule ................................................................................................................................................... 58 5.4 Cost Estimate ....................................................................................................................................................... 59 5.5 Accelerated Bridge Construction .................................................................................................................. 60 5.5.1 Self-propelled Modular Transporter Move ................................................................................... 61 5.5.2 Incremental Bridge Launch ................................................................................................................ 61 5.5.3 Slide-in Bridge Construction .............................................................................................................. 62 5.5.4 Prefabricated Bridge Elements and Systems ............................................................................... 64 6. Traffic Impacts ..................................................................................................................................................... 65 6.1 Existing Traffic Conditions ............................................................................................................................... 65 6.2 Maintenance of Traffic Options ..................................................................................................................... 66 6.3 Bridge Rehabilitation and Two-lane Bridge Construction .................................................................... 68 6.3.1 Alternating Single Lane ....................................................................................................................... 68 6.3.2 Inbound Castle Creek Bridge Lane with Outbound Detour—West End Detour (Power Plant Road) .............................................................................................................................................. 70 6.3.3 Outbound Castle Creek Bridge Lane with Inbound Detour—Temporary Detour across Marolt-Thomas ....................................................................................................................................... 71 6.4 Three-lane Bridge Construction .................................................................................................................... 72 6.4.1 Centered—One-lane Bridge During All Construction Phases with Companion Detour 72 6.4.2 Faster—One-lane Bridge During Phase 1 with Companion Detour; Two-lane Traffic During Subsequent Phases ................................................................................................................. 72 6.4.3 Shifted—Two-lane Bridge During All Phases .............................................................................. 72 7. Overall Project Costs .......................................................................................................................................... 73 7.1 Other Project Costs ............................................................................................................................................ 73 7.1.1 Unlisted Construction Items ............................................................................................................... 73 7.1.2 Planning (NEPA) and Design ............................................................................................................. 73 7.1.3 Right-of-Way and Easements ............................................................................................................ 74 7.1.4 Public Involvement ................................................................................................................................ 74 7.1.5 Construction Engineering and Indirects (CE&I) ........................................................................... 74 7.2 Overall Project Costs .......................................................................................................................................... 75 7.3 Economic and User Costs ................................................................................................................................. 75 8. References ............................................................................................................................................................ 76 Appendix A 2022 Structure Inspection and Inventory Report by CDOT Appendix B H-09-B (Castle Creek Bridge), In-depth Superstructure Investigation Report by Engineering Operations, LLC (eO) 16 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf iii Appendix C Rehabilitation Sufficiency Rating Calculation Appendix D Rehabilitation Cost Estimate Appendix E ABC Method: Incremental Bridge Launch Appendix F ABC Method: Bridge Slide Appendix G Replacement Phasing Options Appendix H Conceptual Bridge Rehabilitation Plans Appendix I Conceptual Two-lane Bridge Replacement Plans Appendix J Conceptual Three-lane Bridge Replacement Plans Appendix K Overall Project Cost Matrix – Bridge Rehabilitation and Replacement Options Table 1. Bridge Feasibility Study Summary ................................................................................................................... 13 Table 2. National Bridge Inventory Standard Coding ................................................................................................. 23 Table 3. Rehabilitation Schedule ....................................................................................................................................... 42 Table 4. Superstructure Depths ......................................................................................................................................... 50 Table 5. Phasing Options Advanced for Consideration ............................................................................................. 53 Table 6. Phasing Option Impact Summary .................................................................................................................... 58 Table 7. Summary of Construction Duration and Impacts ....................................................................................... 59 Table 8. Summary of Alternative Cost Estimates ......................................................................................................... 60 Table 9. Accelerated Bridge Construction Summary .................................................................................................. 64 Table 10. Summary of Maintenance of Traffic Options and Performance ............................................................ 67 Table 11. Estimated Right-of-Way and Easement Costs ............................................................................................. 74 Table 12. Summary of Overall Costs for Options ........................................................................................................... 75 Figure 1. Castle Creek Bridge Location ................................................................................................................................ 1 Figure 2. Rehabilitation Construction Phasing .................................................................................................................. 3 Figure 3. Alternating Single Lane Projected Traffic Queues ......................................................................................... 8 Figure 4. Outbound and Inbound Detour Options During CCB Rehabilitation or Replacement ...................... 9 Figure 5. Three-Lane Centered Bridge Replacement .................................................................................................. 11 Figure 6. Existing Bridge ........................................................................................................................................................ 16 Figure 7. American Association of State Highway and Transportation Officials H20-S16-44 Truck .......... 17 Figure 8. Utilities Along Bridge and Connection at Abutment 1 .............................................................................. 18 Figure 9. Potential Tree Impact Areas ............................................................................................................................... 20 Figure 10. SH 82 Existing Profile ........................................................................................................................................... 21 Figure 11. Condition Rating History of the Bridge ........................................................................................................... 23 Figure 12. Deck Concrete Spall with Exposed Rebar ...................................................................................................... 24 Figure 13. Deck Concrete Spall with Exposed Rebar ...................................................................................................... 25 Figure 14. Significant Corrosion in Web and Top of Bottom Flange of North Exterior Girder A ..................... 26 17 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf iv Figure 15. Girder F Sagging Near Mid-span ...................................................................................................................... 26 Figure 16. Typical Surface Corrosion of Interior Girder – Girder E South Face at Pier 4 .................................... 27 Figure 17. Deflection of Stiffener at North Face of Girder B ........................................................................................ 28 Figure 18. Section Loss in Base of Bearing Stiffener – Girder F at Abutment 6 .................................................... 28 Figure 19. Pack Rust Between Bearing Stiffeners of Interior Girder at Abutment 1 ............................................ 29 Figure 20 Failure of Protective Coating - Typical on All Steel Sections .................................................................... 29 Figure 21. Rocker Bearing Covered in Dirt – Typical at Abutment 1 ......................................................................... 30 Figure 22. Movement of Bearing 6F at Abutment 6 ....................................................................................................... 31 Figure 23. Impending Spall in the Bearing Pedestal at Bearing 6A at Abutment 6............................................. 31 Figure 24. Loose Anchor Bolt Nuts – Typical at All Bearings ....................................................................................... 32 Figure 25. Surface Corrosion of C-Channel Diaphragms – Typical at All Diaphragms ....................................... 32 Figure 26. Exposed Corroded Rebar on Pier Cap at Pier 2 ........................................................................................... 33 Figure 27. Light Scale Cracking at Pier Cap – Typical at All Pier Caps ...................................................................... 33 Figure 28. A Portion of Abutment 1 Backwall Was Removed During Previous Construction ........................... 34 Figure 29. Light Scale, Delamination and Water Staining at Abutment 6............................................................... 35 Figure 30. Inadequate Joint Seal at Abutment 6 ............................................................................................................. 36 Figure 31. Movement of Timber Retaining Wall at Abutment 1................................................................................. 37 Figure 32. Rehab Construction Phasing – Phase 1 (Looking East) ............................................................................ 41 Figure 33. Rehab Construction Phasing – Phase 2 (Looking East) ............................................................................ 41 Figure 34. Site Overview ........................................................................................................................................................... 44 Figure 35. Three-span Configuration ................................................................................................................................... 45 Figure 36. Four-span Configuration ..................................................................................................................................... 46 Figure 37. Approximate Crane Layout Needed to Erect Steel Girders ..................................................................... 48 Figure 38. Example Falsework Photo for Cast-in-place Concrete Construction ................................................... 49 Figure 39. Two-lane Alternative Cast-in-place Concrete Typical Section ............................................................... 50 Figure 40. Three-lane Alternative Cast-in-place Concrete Typical Section ........................................................... 51 Figure 41. Bridge Footprint Required to Overbuild New Bridge Outside of Existing, Deemed Not Feasible ...................................................................................................................................................................................... 52 Figure 42. Two-lane Replace, Bridge Footprint ................................................................................................................ 54 Figure 43. Three-lane Centered, Bridge Footprint .......................................................................................................... 55 Figure 44. Three-lane Faster, Bridge Footprint ................................................................................................................ 56 Figure 45. Three-lane Shifted, South, Bridge Footprint ................................................................................................ 57 Figure 46. Three-lane Shifted, North, Bridge Footprint................................................................................................. 57 Figure 47. Self-propelled modular transporter construction on Minnesota Department of Transportation Maryland Avenue Bridge ..................................................................................................................................... 61 Figure 48. Incremental Steel Bridge Launch at the Athabasca River Bridge .......................................................... 62 18 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf v Figure 49. Slide-in Bridge Construction at the Colorado Department of Transportation State Highway 266 over Holbrook Canal Bridge ............................................................................................................................... 63 Figure 50. Weekday Traffic Counts on SH 82 between Maroon Creek Road and Cemetery Lane .................. 65 Figure 51. Outbound and Inbound Detour Options during Castle Creek Bridge Reconstruction or Rehabilitation .......................................................................................................................................................... 67 Figure 52. Inbound Queue Length with Alternating Single Lanes Across the Bridge ......................................... 69 19 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf vi Acronyms and Abbreviations AASHTO American Association of State Highway and Transportation Officials ABC accelerated bridge construction BDM Bridge Design Manual CCB Castle Creek Bridge CDOT Colorado Department of Transportation City City of Aspen eO Engineering Operations FO functionally obsolete kips pound(s)-force LRFD Load and Resistance Factor Design MASH Manual for Assessing Safety Hardware mph mile(s) per hour NBI National Bridge Inventory NSA not self-arrested PPC polyester polymer concrete ROW right-of-way RTD Regional Transportation District SH 82 State Highway 82 SIBC slide-in bridge construction SPMT self-propelled modular transporter vph vehicle(s) per hour 20 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 1 1. Executive Summary PURPOSE OF THIS FEASIBILITY STUDY Why was this Feasibility Study prepared? The City of Aspen is evaluating the feasibility of either rehabilitating or replacing the State Highway 82 (SH 82) bridge over Castle Creek and Power Plant Road in the City of Aspen, Colorado (City) (Figure 1). SH 82 is the single roadway that connects the City to other towns in the Roaring Fork Valley and beyond and, as such, serves as a vital link for local and regional travelers. Built in 1961, the Castle Creek Bridge (CCB) is a 5-span riveted steel plate girder bridge, with a reinforced concrete deck that rests on top of steel girders. It provides 2 travel lanes and sidewalks on both sides. A complex network of utilities run under the bridge. The existing CCB is a 63-year-old steel bridge on concrete supports. It was designed for vehicular loading less than today’s AASHTO standard code requirements, for a design life of 50 years. Figure 1. Castle Creek Bridge Location 21 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 2 What issues have been identified with the existing bridge? Recent inspections of the 63-year-old bridge have identified several issues, including signs of wear and major deterioration and corrosion of structural steel and concrete bridge components. In a 2022 routine bridge inspection, the Colorado Department of Transportation (CDOT) assigned the CCB a sufficiency rating of 50.3 (out of 100), which ranks the bridge according to structural condition, load rating, traffic data, and public importance. The National Bridge Inventory notes that a detour for the CCB is a 1-mile route that cannot accommodate present traffic volumes or oversize vehicles, impacting emergency response times. The length of this detour affects the sufficient rating of the bridge. The CCB also was designated as functionally obsolete, meaning the bridge and/or approach road alignment do not meet current standards for the highway system of which the bridge is an integral part. A 2023 bridge special inspection ranked the bridge superstructure as “Fair” and revealed several issues with the CCB, particularly with the concrete deck and asphalt overlay and steel girders. The underside of the concrete deck exhibits signs of degradation and widespread surface cracking, and the steel girders show varying degrees of corrosion, with exterior girders displaying considerable corrosion and sag. Numerous tack welds and girder stiffeners exhibit cracks, and protective coatings on steel elements have failed, contributing to accelerated corrosion. Pier caps have water staining, delamination, and cracks. An inadequate joint sealing at Abutment 6 raises concerns about the bridge’s structural performance, and notable movement of the bridge was observed through the existing conditions of the bearings. The timber retaining wall that supports the bike path at a bridge abutment requires yearly adjustments to keep the wall vertical (see Section 4.2 of this Feasibility Study for details). BRIDGE REHABILITATION ANALYSIS What bridge rehabilitation measures are feasible? Given the considerable deterioration of bridge components, a comprehensive rehabilitation plan is essential and would include bearing replacement, exterior girder replacement (requiring sidewalk replacement), protective steel coating rehabilitation, tack weld removal and monitoring, concrete deck repairs and asphalt overlay, pier cap repairs, joint seal replacement, and bridge rail replacement (see Section 4.3 for details). Regular monitoring and inspections would be crucial to evaluate the effectiveness of the rehabilitation measures and to promptly address issues as they emerge. Deck concrete spall with exposed rebar Considerable girder corrosion Hole in girder stiffener Bearing pedestal crack Movement of timber retaining wall 22 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 3 Will rehabilitation fix all the issues with the bridge? The rehabilitation measures would address the bridge’s immediate maintenance needs, prevent further deterioration, and maintain its structural integrity and safety while improving the bridge’s long-term durability. Rehabilitation would not raise the load rating of the bridge to current standards, reduce maintenance needs, or address the limited functionality of the narrow roadway width. As such, the CCB would still be rated functionally obsolete. Further, the sufficiency rating of the bridge would not greatly increase because issues such as the narrow travel way width would not be addressed by rehabilitation measures. The extent to which rehabilitation measures would extend the bridge’s service life would depend on factors such as routine maintenance (see Sections 4.3 and 4.4 for details). In short, rehabilitation measures would not substantially improve the bridge’s condition to a level where total replacement would not be deemed necessary. How would you implement rehabilitation activities? To minimize disruptions to traffic during construction, a phased construction approach would be most feasible. This approach would keep part of the bridge open during construction, with one lane open while Rehabilitation would not address all issues with the current bridge. One-inch bend in stiffener Failure of protective coating Bearing movement at Abutment 6 Inadequate joint seal at Abutment 6 Light scale cracking typical at all pier caps Figure 2. Rehabilitation Construction Phasing Rehabilitation Construction Phase 1 (Looking East) Rehabilitation Construction Phase 2 (Looking East) 23 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 4 construction is completed on one section of the bridge, then shifting traffic to the other side of the bridge to complete construction (Figure 2). Pedestrian access would be maintained on the bridge in a similar fashion. One temporary lane would be used and traffic movement would be maintained using either a signalized alternating lane or a single lane across the bridge in one direction paired with a companion detour in the other direction. The phasing options evaluated in this analysis could accommodate traditional snowplows and smaller wide loads (snowcats), but not larger snowcats due to space constraints (see Section 4.5 and 6 for details). Temporary or permanent utility relocations would be conducted in phases to maintain uninterrupted service during construction. How long would it take to rehabilitate the bridge? Rehabilitation would occur in two phases – each lasting approximately 4 to 6 months as dictated by area weather conditions and community events in Aspen and surrounding areas. One phase would be completed per year; therefore, bridge rehabilitation would be completed in two years. BRIDGE REPLACEMENT ANALYSIS What bridge replacement options were evaluated? The following two bridge width alternatives were evaluated for a bridge replacement: Two-Lane Bridge Alternative: This alternative would provide a two-lane bridge similar to the existing bridge, with one 10-foot sidewalk on the north side to accommodate the City’s construction future planned trail. However, it would require of a temporary access lane that would be left in place, resulting in an approximately 48-foot-wide bridge, which would be only slightly narrower than the three-lane alternative. Three-Lane Bridge Alternative: This alternative would provide a three-lane bridge with one 10-foot sidewalk on the north side, and provide the flexibility to designate one lane for immediate and future transit use. This bridge would be approximately 52 feet wide – only slightly wider than the two-lane alternative. What type of bridge would be built? Several bridge types were evaluated, including precast concrete, steel, and cast-in-place concrete bridges. The steep terrain and facilities under the bridge limit the space for large cranes, eliminating the ability to use precast concrete. Crane placement for steel requires closures of Power Plant Road. Therefore, only cast-in-place concrete is considered feasible because it provides the best constructability and limits impacts to the SH 82 profile. In addition, it was found that a four-span bridge would provide the best opportunity to control span lengths for a shallower structure depth that would accommodate traditional phased construction. Bridge replacement alternatives would be designed to current design standards and support heavier vehicle loads. Three-Lane bridge provides transit lane options now and into the future. Bridge rehabilitation would be completed in 2 years. However, the bridge would remain in the “functionally obsolete” classification. 24 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 5 How would you phase construction of a replacement bridge? With the need to keep SH 82 partially open to traffic during construction, phased construction options were evaluated, all of which would keep portions of the existing bridge open to at least one lane of traffic during construction. (Full bridge demolition/construction would only be an option if a new inbound/outbound detour is built to shift all SH 82 traffic from the bridge site to reduce traffic impacts.) Traffic would be shifted from one part of the bridge to the other as portions of the new bridge are completed. An “overbuild” option was evaluated, which involves building a wider bridge than required for the final bridge in order to accommodate traffic during construction. This was eliminated as a feasible option because of spatial constraints at the bridge site and costly right-of-way that would be required. Temporary lanes would be required on both portions of the existing and new bridge during construction to prevent a full closure of SH 82. The phasing options evaluated in this analysis could accommodate traditional snowplows and smaller wide loads (snowcats), but not larger snowcats due to space constraints. Pedestrian access would be provided either along the bridge or rerouted underneath the bridge, depending on the construction phase (see Section 5.3. for details). In all construction phasing options, utilities would be protected and relocated prior to demolition of existing bridge components. Two-lane bridge construction phasing One phasing option for this alternative was considered, because the only other option would be to fully close and replace the existing bridge. Four phases of construction would be required, but a single lane of traffic would be able to remain open during all construction phases while a detour lane would handle the other direction of travel. A temporary travel lane would be built on the bridge for use during construction and would remain in place after construction completion. As such, the width of the new two-lane bridge would be approximately 8 feet wider than the existing bridge. The new bridge would be located within the existing right-of-way limits; therefore, no right-of-way acquisition would be required. All phasing options would carry traffic on the bridge in a partial state throughout construction. Full bridge demolition and construction is only an option if a new inbound/outbound detour is built to shift all traffic from bridge site to reduce traffic impacts. 25 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 6 Three-lane bridge construction phasing Three construction phasing options were evaluated for the three-lane bridge replacement alternative, as summarized below. Three-Lane Centered: Phasing under this option is similar to the two-lane alternative. The main difference is that the bridge segments would be wider to accommodate the width for a third lane. The bridge would be located within the existing right-of-way limits; therefore, no right-of-way acquisition would be required. Three-Lane Faster: This option would demolish portions of the existing bridge early in the first phase to allow earlier construction of two temporary lanes, thus limiting the need for a single lane to one phase. However, pedestrians would be rerouted under the bridge in all phases. This option would shift the bridge approximately 3 feet to the south to avoid residences to the north, resulting in right-of-way impacts and removal of nearby trees. However, the south edge of the new bridge would almost be above the residence on Harbour Lane. Additional care would be required during construction to protect this residence. Three-Lane Shifted: This option would maintain two lanes on the bridge during all construction phases. Similar to Faster, this option would shift the new bridge to the south to avoid residences to the north, and as a result, the residence on Harbour Lane would nearly be under the bridge. The shift to the south would require rebuilding road segments at both ends of the bridge to align sidewalks. Like Faster, this option would extend outside existing right-of- way, affecting nearby residences and potentially requiring additional right-of- way acquisitions. A variation was considered that would provide pedestrian access during all phases by adding a pedestrian path on the bridge, but this would shift the bridge farther south, placing the bridge over a residence and resulting in right-of-way impacts. Therefore, it would not be feasible to accommodate pedestrians during all phases of this option. What would a new bridge look like? Aesthetic guidelines for a replacement bridge have not been established. If a bridge replacement alternative is selected, aesthetic features would be incorporated into the bridge design as required by the City, CDOT, and other involved parties. How long would it take to build a new bridge? A construction phase would last approximately 4 to 6 months as dictated by area weather conditions and community events in Aspen and surrounding areas. One phase would be completed per year. Total construction duration would be four years for Three-Lane Centered and Shifted, and three years for Three-Lane Faster. New bridge construction would be completed in 3 or 4 years, depending on phasing option chosen. The Three-Lane Centered bridge would provide the best overall scenario for construction; however, it would result in the most impacts to vehicular and pedestrian travelers. The Three-Lane Shifted bridge would be the best scenario for vehicular and pedestrian travelers but would encounter substantial project risks and property impacts. 26 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 7 Can accelerated bridge construction methods be used to build a new bridge? Several accelerated bridge construction (ABC) techniques were analyzed to determine which, if any, would be a good fit for this spatially constrained site. ABC typically reduces onsite construction time and improves site constructability, total project delivery time, and work-zone safety for the traveling public. It can also reduce traffic impacts during construction and weather-related time delays. ABC methods considered include self-propelled modular transporter bridge move, bridge launch, bridge slide, and prefabricated bridge elements. These techniques involve various methods of building new bridge components off-site or near the bridge site and transporting/moving them into place once the new bridge substructure is built. It was determined that these ABC methods would not be successful for the CCB because of site terrain and space constraints for assembling and operating the large cranes required to move the heavy bridge components into place, larger construction footprint that impedes on ROW or other facilities, and/or lack of a viable detour during an extended closure of SH 82 (see Section 5.5 for details). Considering these issues, traditional bridge construction phasing or a full closure of SH 82 (where the existing bridge is demolished and rebuilt with traffic on a detour) are the only feasible options. TRAFFIC IMPACTS DURING CONSTRUCTION How would traffic be handled during construction? Existing traffic volumes are highest during morning and evening peak travel hours. The 2022 West End Traffic Study (Fox Tuttle 2022) estimated outbound (westbound) traffic at 1,000 to 1,250 vehicles per hour (vph) on SH 82 and 600 to 650 vph at Power Plant Road during the evening peak hours. No recent estimates of inbound (eastbound) traffic volumes in the morning peak hour are available; however, inbound traffic backups and congestion commonly occur on SH 82 between 7:00 a.m. and 9:00 a.m. during the weekdays. Considering the critical need to minimize traffic flow disruptions to and from the City, total bridge closure is impractical. Therefore, phased construction approaches were evaluated that would keep at least one lane open on the bridge during bridge rehabilitation or replacement, as summarized below. Bridge Rehabilitation and Two-Lane Bridge Replacement Alternative Three options were considered to accommodate traffic during bridge rehabilitation or construction of a two-lane bridge replacement, as summarized below. Total bridge closure during rehabilitation is impractical – this would be avoided with a two- phased construction approach. Use of ABC would be a good option if the only consideration was reducing impacts to the traveling public. However, the proximity of nearby residents, tight curves of the roadway below the bridge, and narrow footprint of the CCB make most ABC options very problematic. Traditional bridge construction phasing or full closure of SH82 are the only reasonable options. 27 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 8 Alternating Single Lane: Temporary signals would be placed at each end of the bridge to operate an alternating-direction single lane on the bridge. While buses could be moved to the front of the queue where space permits, overall this option would result in substantial delays for transit and school buses and emergency response times. To accommodate emergency evacuations, outbound traffic would have right-of-way on the single lane; however, evacuation times would increase. Pedestrian access would be accommodated. As Figure 3 shows, this option would result in extremely long traffic queues and gridlock. Evacuation times also would be untenable and, therefore, this option was not deemed reasonable. Inbound CCB Lane with Outbound Detour—West End Detour (Power Plant Road): One lane of (outbound) traffic would detour down North 7th Street to West Smuggler Road and Power Plant Road while inbound traffic would use one lane over the bridge during phased construction (Figure 4). This option may require one-way movement and improvements to Power Plant Road to accommodate large vehicles and improve traffic capacity. Use of temporary signals and modifying existing signal cycles, as well as increasing bus service to the Brush Creek Intercept Lot, would be explored to improve traffic flow, however up to 5-hour travel delays would persist. Travelers accessing the hospital and high school or evacuating during emergencies would experience delays. Use of construction protocols such as transit and school bus priority on SH 82 and providing right-of-way to outbound traffic during an emergency evacuation would reduce travel delays for these vehicles and users. Also, both bridge construction or rehabilitation may require periodic closure of Power Plant Road, impacting the reliability of this detour. Alternating Single Lane phasing across the bridge would cause large traffic queues in the Inbound direction (reaching past Basalt, CO) and grid lock in the city. A West End Detour via Power Plant Road could be improved to serve as an outbound detour during construction. Despite the improvements it would experience large travel delays and not be a reliable detour option. Figure 3. Alternating Single Lane Projected Traffic Queues 28 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 9 Outbound CCB Lane with Inbound Detour—Temporary Detour Across Marolt-Thomas: In this scenario, a temporary one lane detour route would be built along an existing transportation easement to split one lane of eastbound (inbound) traffic from SH 82 to the south across the Marolt-Thomas open space, span Castle Creek with a temporary bridge, and join SH 82 on West Main Street (Figure 4). This detour route could accommodate peak morning traffic volumes and maintain one lane on the CCB for westbound (outbound) peak evening traffic. Access to the hospital and high school would be similar to existing conditions. The outbound detour route would experience minor construction delays, but the inbound route would remain open during construction and experience no delays. The temporary detour could be removed after construction completion. For emergency evacuation, the inbound detour lane could be reversed and serve as outbound egress in conjunction with CCB outbound lane. This detour option would provide an additional evacuation route during construction and, if desired, the temporary bridge could remain in place for future evacuation needs. Safe pedestrian and bicycle traffic could be provided along this detour route. Three-Lane Bridge Replacement Alternative Two options were evaluated that would use the open lane on the bridge in one direction and a companion detour in the other direction to accommodate traffic during construction. These options are summarized below and shown on Figure 4 (see Section 6.4 for details). Centered (One-lane bridge during all construction phases with companion detour): Under this option, the bridge would be optimally placed to minimize construction impacts. This option would provide a single lane of traffic on the bridge paired with an inbound detour, as described for the Bridge Rehabilitation and Two-Lane Bridge Replacement alternatives, and would result in similar traffic impacts during construction. Pedestrian access across the bridge would be maintained with the use of an outbound detour or diverted over to the inbound detour with minimal to no interruptions (see Section 6.4.1). Construction phasing for this option is shown on Figure 5. The inbound detour across Marolt-Thomas is the most reliable option – minimizes travel delays, prioritizes transit services, provides continual safe pedestrian access, and doubles as evacuation route during construction. If desired, this detour could also be evaluated for carrying two lanes of traffic (inbound and outbound), allowing for faster replacement or rehabilitation of the CCB. Figure 4. Outbound and Inbound Detour Options During CCB Rehabilitation or Replacement 29 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 10 Faster (One-Lane bridge during Phase 1): This option would shift the bridge to the south to provide sufficient width to build two continuous lanes (inbound and outbound) that would be used during all construction phases except Phase 1. During Phase 1, a single outbound lane on the bridge in conjunction with an inbound detour would serve both directions of travel. As such, the detours and traffic impacts for Phase 1 would be the same as those described for the Bridge Rehabilitation and Two-Lane Bridge Replacement alternatives above. Traffic under all other phases would be similar to existing conditions, where both lanes would be converted to facilitate outbound flow during an evacuation event. Pedestrians would be rerouted under the bridge or over to the inbound detour for all phases, and pedestrian access would be impacted when construction impacts the path below the bridge (see Section 6.4.2). Shifted (Two-lane bridge during all phases): This option would require an overbuild of the replacement bridge. Two traffic lanes would be maintained during construction, resulting in minimal traffic impacts. Construction may constrain S-Curve traffic flow for short periods, but queues and delays would not be a noticeable change from existing conditions. Pedestrians would use the northern sidewalk until the final phase, during which they would be rerouted to Power Plant Road (see Section 6.4.3). 30 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 11 Figure 5. Three-Lane Centered Bridge Replacement 31 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 12 EXISTING CONDITIONS IN THE STUDY AREA What potential environmental concerns are present in the study area? A detailed assessment of the environmental setting of the study area was not conducted for this study. However, potential environmental concerns include effects to Castle Creek, wetlands, potentially hazardous materials (lead paint on bridge), recreational trails, open space, historic properties, and trees/vegetation. Construction activities could affect water quality and habitat for aquatic and terrestrial species in the short term, and trees and vegetation near the bridge would be impacted by bridge replacement alternatives. The CCB was deemed to not be eligible for the National Register of Historic Places. Long term impacts are not anticipated for the recreational trail, wildlife, air quality, water quality, archaeological, or paleontological resources. However, an environmental assessment would be required to assess existing environmental conditions and potential impacts from bridge construction, operation, and maintenance activities. COSTS How much would bridge rehabilitation and bridge replacement alternatives cost? Potential overall costs at this early feasibility stage are estimated at approximately $45 million for bridge rehabilitation, $69 million for a concrete Two-Lane Bridge Replacement, and $73 million for a concrete Three-Lane Centered Replacement Bridge. For more details, see Table 1 in this Executive Summary and Section 7. FEASIBILITY ANALYSIS SUMMARY Bridge Rehabilitation Analysis Feasible rehabilitation measures to address current deterioration of steel and concrete bridge components (refer to Section 4.2) include replacing bearings, exterior girders, and bridge railing; rehabilitating steel protective coating; removing tack welds; and repairing pier columns and caps. Refer to Section 4.3. It is unlikely that rehabilitating the bridge would substantially improve its sufficiency rating, prolong its service life, or change its “functionally obsolete” classification. Refer to Sections 4.3 and 4.4. Bridge rehabilitation would require relocating several critical utilities running along the existing bridge that serve the City, which poses a considerable construction challenge. Refer to Section 4.5. Bridge rehabilitation would require closure of one lane of the existing bridge for approximately 4 to 6 months combined with the use of detour route, which An Environmental Assessment would be required to assess existing environmental conditions and potential impacts from bridge construction, operation, and maintenance. 32 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 13 would temporarily impair traffic operations. Refer to Section 6.3 and Section 6.4. Bridge Replacement It was determined that a four-span, post-tensioned, cast-in-place concrete girder bridge would be the most feasible option for a replacement bridge. Refer to Sections 5.2 and 5.3. Limited space is available to construct the new bridge because of the proximity of residential structures and prohibitive costs of potential right-of- way (ROW) requirements. Refer to Section 5.3. Phased construction would be required to maintain access to SH 82 during construction. Traffic would be reduced to one outbound lane over the bridge, and inbound detour also would be used. Pedestrian access across the bridge also would be limited during construction or rerouted along the inbound detour. Refer to Section 5.3 and Section 6.4 The bridge replacement is estimated to take approximately 4 years of construction, working around the restrictions of major events and winter weather. Refer to Section 5.3.3. Table 1 compares key features and elements of the bridge rehabilitation and replacement options. Color shading denotes how each option compares to others as follows: red (poor), yellow (fair), green (good). Table 1. Bridge Feasibility Study Summary Construction Issues Rehabilitation Two-Lane Bridge Replace Three-Lane Bridge Centered Maintenance of Traffic • SH 82 remains accessible; traffic maintenance and inbound detour required. • Oversized loads (>14 feet) not accommodated on SH 82 CCB. • SH 82 partially accessible; traffic maintenance and inbound detour required. • Oversized loads (>14 feet) not accommodated on SH 82 CCB. • Same as Two-Lane Bridge Replace. Traffic Travel Time Impacts • Inbound detour (Marolt- Thomas), no substantial delay. • Outbound lane phased across existing CCB with delays similar to existing conditions. • Inbound detour (Marolt- Thomas), no substantial delay. • Outbound lane phased across CCB with delays similar to existing conditions. • Same as Two-Lane Bridge Replace. Pedestrian and Bicycle Access • Access via bridge provided during all phases • Access via bridge not provided during all phases. • Access provided via reroute under bridge on existing trail or along Inbound detour (Marolt-Thomas). • Same as Two-Lane Bridge Replace. 33 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 14 Construction Issues Rehabilitation Two-Lane Bridge Replace Three-Lane Bridge Centered Utilities (Gas, Fiber, Copper) • No impacts to SH 82 traffic. • Utility relocation required. • No impacts to SH 82 traffic. • Phase 1 duration extended to relocate utilities to new bridge. • Same as Two-Lane Replace. Schedule • Construction period anticipated to be shorter than replacement alternatives. • Weather and summer event shutdown period restricts construction window, prolonging construction. • Construction completed in 2 years. • Weather and summer event shutdown period restricts construction window, prolonging construction. • Longer construction period than rehabilitation alternative. • Construction completed in 4 years. • Same as Two-Lane Bridge Replace. Right-of-Way Impacts • No ROW impacts anticipated. • Temporary construction easements (TCE) may be required for access. • No ROW impacts anticipated for alternative shown in Appendix I. • ROW limits restrict construction north/south of existing bridge. • Temporary construction easements (TCE) may be required for access. • No ROW impacts anticipated for alternative shown in Appendix J. • ROW limit restrictions and TCEs for access same as Two-Lane Bridge Replace. Constructability • Minimal impact to Power Plant Road and facilities under bridge. • Crane locations for girder erection are challenging around the existing facilities below the bridge. • Falsework would accommodate facilities under bridge. • Facilities under bridge and nearby residences restrict construction method options. • Same as Two-Lane Bridge Replace. Enables Transit Priority and Future Transit • Provides bus transit in existing general traffic lanes. • Cannot handle future Light Rail Transit (LRT) loads. • Provides bus transit in new general traffic lanes. • Cannot handle future Light Rail Transit (LRT) loads. • Provides bus transit priority lane in outbound direction. • Designed for future Light Rail Transit (LRT) loads. 34 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 15 Construction Issues Rehabilitation Two-Lane Bridge Replace Three-Lane Bridge Centered Bridge Service Life • No substantial service life extension. • Would remain functionally obsolete for roadway width. • Would not meet current design code requirements. • 75-year service life with standard bridge maintenance. • Would meet current design code requirements. • Future widening of bridge to accommodate future traffic and transit demands would be challenging. • 75-year service life with standard bridge maintenance. • Would meet current design code requirements. • Would accommodate future traffic and transit demands. Overall Project Costs (2024)* $44 million $69 million $73 million • Construction Costs 63% 62% 62% • Planning and Design 8% 12% 13% • ROW/TCE’s 10% 7% 6% • Construction Management/PI 18% 19% 19% * See Section 7 for explanation of Overall Project Costs, including structural bridge costs, which are detailed in Section 4.7 and Section 5.4. ^percentage of total costs 35 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 16 2. Site Description and Design Features This section summarizes the site description and design features of CCB. 2.1 Existing Structure CCB is a 5-span riveted steel plate girder continuous bridge that carries SH 82 over Castle Creek and Power Plant Road. Originally constructed in 1961, the superstructure is made of a reinforced concrete deck resting on top of steel girders. The bridge is 423.6 feet long and 40 feet wide (out-to-out), with two vehicular lanes and sidewalks on each side. The bridge uses steel plate girders under the vehicular portion of the deck and rolled steel wide flange girders to provide the main support for each sidewalk. Steel girders are supported by rocker bearings at Abutment 1 (West) and Piers 2, 3, 4, and 5. Pinned bearings support steel girders at Abutment 6 (East). There is a new approach slab with a modular expansion joint constructed in 2022 to replace the original failed backer rod–type expansion joint at Abutment 1 (West). The superstructure is supported by reinforced concrete piers resting on spread footings 3 feet thick, 8 feet wide, and 12 feet long. The piers have tapered columns and vary in height: Pier 2 stands at 55 feet, Pier 3 at 63 feet, and Pier 4 and Pier 5 at 68 and 40 feet, respectively. Figure 6. Existing Bridge The current structure was designed to withstand H20-S16-44 vehicular live loading, which was renamed to HS20-44 loading after 1965. The H20-S16-44 designation indicates the vehicle tractor axles (two axles) combined are 20 tons, with semi-trailer weight of 16 tons, as published in 1944. Combined, the gross vehicle weight is 36 tons, as shown on Figure 7. At the time of this bridge design, code required design for either a design truck or design lane load, which simulates a series of trucks. After 1993, the code changed to requiring design toward a design truck combined with a design lane load. 36 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 17 Figure 7. American Association of State Highway and Transportation Officials H20-S16-44 Truck 2.2 Traffic Detours The detour length recorded in the National Bridge Inventory (NBI) for CCB is 0.6 mile. However, it involves vehicles descending into the Castle Creek area via Power Plant Road. This detour cannot accommodate present traffic volumes, impacting travel times and emergency response when used. Also, the detour route does not meet the current requirements of transit vehicles (buses) and oversize vehicles on SH 82. The length of this alternative route affects the sufficiency rating of the current bridge based on the Colorado Structure Element Level Coding Guide evaluation system conducted by the Colorado Department of Transportation (CDOT). Generally, when work is being performed on SH 82 in the bridge area, transit traffic receives priority through traffic management. For additional information related to the existing detour and potential alternative detours during construction, refer to Section 6. 2.3 Utilities Being the singular linkage between Aspen and other towns in the Roaring Fork Valley, CCB accommodates several utilities essential for the operational support of Aspen. A complex network of City fiber optic lines run under the bridge. The 96-strand cables run directly along the north side of the bridge, connecting to a utility cabinet above the bike path on the west side at Abutment 1. These fibers play a pivotal role in networking and connectivity for City and county facilities, including the 911 dispatch center. The cables have minimal slack available to accommodate movement or relocation. Relocation of these communication lines will be part of the project cost. The existing Castle Creek Bridge is a 63-year-old steel bridge on concrete supports. The bridge was designed for vehicular loading less than today’s American Association of State Highway and Transportation (AASHTO) standard code requirements for a design life of 50 years. Power Plant Road is currently the only detour for SH82 (Hallam Street). Roadway improvements would be required on Power Plant Road if it were relied upon as the detour route during bridge construction. Alternatively, a separate detour route could be constructed to accommodate traffic during construction. 37 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 18 A communication provider, Comcast, also runs their fiber infrastructure along the bridge, and any disruption to this service could lead to a loss of all services for the downtown and surrounding areas. Comcast has a 96-strand cable and 72-strand cable, for which a relocation from manhole to manhole could be a significant relocation. Lumen Technologies, Inc., runs six conduits carrying both copper cables and fiber optics along the bridge for communications, with critical circuits that cannot be removed or disrupted. Ting, Inc., also leases fiber lines from Lumen Technologies, Inc., as a communications provider. Any relocation of these conduits would run vault to vault; however, there is currently no slack in the copper lines to easily accommodate that relocation. Relocation requires new 8-way duct, with an anticipated duration of 8 weeks for relocation. While no gas lines are directly attached to the bridge superstructure, a partially exposed high pressure gas line runs immediately in front of the west Abutment 1, the main gas feed to the City. This line will likely require relocation to ensure safety during construction. Also, a steel gas line is under Power Plant Road below the bridge. A gas regulator station is south of the west end of the bridge, with high pressure gas in/out of the facility. Near the west approach to the bridge, CDOT has a weather sensor puck on the north side of SH 82. Any relocation of this weather sensor puck would be part of the project cost. Finally, the Aspen Sanitation District notes an 8-inch diameter polyvinyl chloride (PVC) main sewer line under the bridge at the valley bottom in Harbour Lane in between Piers 4 and 5, susceptible to potential impacts from modifications to Harbour Lane or Power Plant Road. In addition, there are other sewer mains at either end of the bridge that may be affected by modifications to the bridge approaches. For costs associated with the utility relocations, refer to Section 7. Figure 8. Utilities Along Bridge and Connection at Abutment 1 38 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 19 2.4 Geotechnical Summary A geotechnical field investigation has not been conducted at this conceptual stage of the project. Boring information provided on the existing bridge as-builts (CDOH 1954) show sand and gravel is present between the existing grade and the bottom of the existing footings. It is anticipated deep foundations would be the proposed foundation type for the replacement alternatives considered. Drilled shafts and driven piles are commonly used on CDOT projects throughout the state. Deep foundations have the benefit of requiring less area for their construction compared to spread footing, which would be helpful in reducing impacts to the facilities and residents under the bridge. Deep foundations are also beneficial near waterways such as Castle Creek, mitigating instances of undermining a shallow foundation from water movement. The rehabilitation work discussed in this report would not require work on or around the existing footings, and therefore, the existing soil conditions are not of concern. 2.5 Hydraulic Summary No hydraulic report is available at this stage of the project. The replacement alternatives would remove the existing Pier 4 from Castle Creek to eliminate obstructions to the waterway. Free board is not a concern because of the height of the superstructure. Work within Castle Creek would be required to remove the existing pier, initiating a Section 404 permit for Waters of the U.S. and Wetlands. The rehabilitation work discussed in this report would not affect the piers or foundation elements of the bridge. Therefore, hydraulics is not a concern for the rehabilitation alternatives. Scour does not present a concern based on the visual inspection. 2.6 Environmental Concerns Investigation of environmental constraints and concerns was not conducted for this report. This section highlights known or potential environmental issues based on field observation. Construction for both the rehabilitation and replacement alternatives would take place above Castle Creek with some work within the creek, likely requiring a Section 404 permit for temporary impacts to Waters of the U.S. A wetland delineation in the project would be conducted to further assess any impacts. Replacement work associated with removing and replacing piers in the Aspen Streets Department parking lot would be near the fuel station and its associated storage tank. This could require hazardous material investigation before any subsurface work and careful consideration toward placing any foundation elements outside of any zones with hazardous materials present. Because of the age of the bridge, lead paint may be present. Sample testing will be needed before any construction activities involving the existing steel girders. Overall, existing utilities constitute a complex and interconnected web of service to the community that demands careful consideration in any construction or modification efforts on the existing CCB. Any bridge work impacting the support for the existing utilities will require relocation to another location on the bridge or to a separate temporary support structure for the utilities. 39 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 20 During construction, temporary impacts are expected for the recreation trail near the west abutment underneath the bridge. Permanent impacts to the trail are not anticipated, but the temporary impacts would require evaluation. Trees and surrounding vegetation may be impacted because of the bridge replacement alternatives. Trees near the northern and southern edge of the existing bridge at the east abutment would be near the proposed edge of deck for some of the phasing options considered in Section 5.3.2, as shown on Figure 9. Trees along the banks of Castle Creek, near Power Plant Road and Harbour Lane, may also be impacted during construction from the installation of new piers and falsework. Impacted trees may require removal or relocation and would need to be coordinated with the City. Figure 9. Potential Tree Impact Areas The bridge was reviewed in a CDOT-prepared statewide inventory of historic bridges and deemed to not be eligible to the National Register of Historic Places. Short-term air quality impacts, including greenhouse gas impacts, would result from bridge construction. Impacts generally would be proportional to traffic delays and queues, with the highest increase in emissions caused by queuing traffic. Longer term, air quality emissions from the three-lane bridge rehabilitation options are expected to be lower than two-lane options because of reduced congestion from three-lane options, thereby reducing emissions from queued traffic. The three lane options are not expected to induce travel demand (and higher emissions) because of the transportation management measures in place on the SH 82 corridor. Short term impacts associated with construction activities could affect water quality and habitat for aquatic and terrestrial species. Long term impacts are not anticipated for wildlife, air quality, water quality, archaeological, or paleontological resources. However, environmental assessment would be required for any bridge action to move forward. 40 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 21 2.7 Roadway Design Features The existing bridge carries SH 82 over Castle Creek, Power Plant Road, and Harbour Lane. Two sidewalks are 8 feet wide at the northern edge of the bridge and 5 feet wide at the southern edge. A project in 2018 widened the northern sidewalk from 5 feet and added a traffic barrier adjacent to the roadway. The roadway is 27 feet wide from curb to curb and accommodates two 11-foot lanes and two 2-foot-6-inch shoulders. The deck has a crowned cross-slope of 1% +/- that slopes away from the centerline of the roadway (City of Aspen 2017). The bridge is built along a tangent section of the SH 82 alignment; however, beyond the bridge limits, there are horizontal curves. A 100-foot-long vertical curve at the center of the bridge alignment within Span 3 begins and ends on the bridge. The tangent that extends to the west has a slope of 0.2%, and the tangent to the east has a slope of 0.2% (CDOH 1954). 3. Structural Design Criteria This section summarizes the structural design criteria for CCB. 3.1 Design Specification and Criteria The bridge replacement alternatives considered in this report would be designed per the latest AASHTO Load and Resistance Factor Design (LRFD) Bridge Design Specifications (AASHTO 2020) and the CDOT Bridge Design Manual (BDM) (2023a). In considering rehabilitation, upgrading the bridge to meet current code might be cost prohibitive. Usually, the AASHTO Load Factor Design methodology serves as an alternative; however, discussions with the bridge owner are essential in this context. Jacobs discussed with City staff the potential of the bridge alternatives carrying a future light rail guideway in and out of Aspen. The conceptual design does not preclude a transit component in the future, accommodating for light rail transit in the evaluation. The Regional Transportation District (RTD) Light Rail Facility Design Guidelines and Criteria (RTD 2018) was used for additional loading and design requirements because the Roaring Fork Transportation Authority does not currently have separate light rail design requirements to reference. 3.2 Loading For a bridge replacement, LRFD would be used for the bridge design and other structural items such as retaining walls. This is the current design approach specified in the CDOT BDM (2023) and a CDOT technical memorandum dated December 7, 1998. HL-93 and permit live load vehicles, in addition to contributing dead loads and pedestrian loads, would be calculated for LRFD load combinations. The bridge elements will be designed for the applicable service, strength, and extreme limit states. If the bridge alternatives are required to carry light rail traffic in the future, additional live load cases would need to be considered to include the RTD Light Rail Vehicle. Figure 10. SH 82 Existing Profile 41 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 22 Over time, AASHTO and CDOT have increased the design vehicle loadings to accommodate heavier vehicles that use roadways as compared to the original interstate system. Any rehabilitation will maintain the H20-S16-44 as the design vehicle for the bridge because the existing bridge will not provide sufficient capacity for the additional loading of an HL-93 vehicle. This same loading limitation was noted in the SH 82 Reversible Lane Feasibility Study (SGM 2008) done over 15 years ago before the HL-93 vehicle introduced in today’s code. 3.3 Aesthetic Requirements Aesthetic guidelines have not been established at this time. Should any replacement effort advance to preliminary design, aesthetic features can be incorporated into the design by Jacobs as required by the City, CDOT, and other involved parties. 4. Bridge Rehabilitation Feasibility This section summarizes the feasibility of bridge rehabilitation. 4.1 Bridge Condition Assessment Recent inspections of the bridge have highlighted areas of concern, indicating signs of wear, major deterioration in several girders, and localized structural concerns. Routine inspection carried out by CDOT in September 2022 (CDOT 2022) assigned a sufficiency rating of 50.3, which is a rating procedure with a numeric value ranging from 0 to 100 indicative of bridge sufficiency to remain in service. A bridge's sufficiency rating is a comprehensive assessment that considers factors such as structural condition, load rating, traffic data, and public importance. Calculated using a formula outlined by the Federal Highway Administration, the rating reflects the bridge's ability to remain in service and compares the existing bridge to a new one meeting current engineering standards. The same assessment also designated the bridge as functionally obsolete, meaning the deck geometry, load-carrying capacity, clearance, or approach roadway alignment no longer meet the current standards for the highway system of which the bridge is an integral part. Refer to Appendix A for CDOT’s inspection report. The sufficiency rating also considers the load rating of the bridge structure. All structures require a load rating defining their long term high frequency live load (traffic) capacity. The NBI rating for the CCB structure is 24.6 tons. The minimum inventory load rating goal for any structure on a state highway is 36 tons. Each element of a bridge is coded during a bridge inspection, from 0 to 9 based on their condition state within NBI Standards. The code is dependent upon the defect location, frequency, and condition. Bridge replacement alternatives are designed in compliance with current design codes. A bridge rehabilitation cannot be upgraded to meet current design codes without significant cost implications. Over the remaining service life of the rehabilitated bridge, heavier vehicles introduced to the roadway system may be limited on this route. 42 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 23 Table 2. National Bridge Inventory Standard Coding Condition Code Description Current Code for CCB Major Elements 7-9 “Good”: From Good to Excellent 5-6 “Fair”: From Fair to Satisfactory Deck (6), Superstructure (5), Substructure (6) 0-4 “Poor”: From Failed to Poor Figure 11 illustrates superstructure and substructure condition code history of the bridge based on the NBI database (NBI 2024). During a 2009 inspection, (CDOT 2009) a decline in the superstructure condition code to 3 (“Poor”) was noted, necessitating immediate attention. According to CDOT records, extensive repairs and rehabilitation efforts were implemented on the bridge in 2011 to improve the condition code of the bridge. Despite these substantial rehabilitation efforts, they were only sufficient to elevate the superstructure to a ”Fair” code. Figure 11. Condition Rating History of the Bridge Source: NBI 2024 It should be noted Figure 11 does not include the deck element, which has maintained a code of 6 for over 30 years. Because the deck has an asphalt overlay, inspectors can usually only assess the deck condition from the underside, meaning some issues may be covered by the overlay. City staff have confirmed deck repairs were performed during the 2018 project that milled off the existing overlay to place a new waterproofing membrane and overlay. This project uncovered some areas requiring full depth deck repair and additional reinforcing where corrosion or impact was noted. Replacing the overlay was challenging because of inconsistencies with the existing bridge deck surface. From November 28 to November 30, 2023, a team of two inspectors used an Under Bridge Inspection Truck to conduct an arm’s length inspection of the steel superstructure. The “In-depth Superstructure Investigation Report” (eO 2023) by Engineering Operations, LLC (eO), produced a comprehensive steel superstructure inspection that confirmed CCB’s (H-09-B) superstructure is in fair condition, substantiating an NBI Item 59 rating of 5 per CDOT’s 2022 inspection. The full inspection report is provided in Appendix B. 43 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 24 4.2 Summary of Field Inspection This section summarizes the findings of the bridge inspection carried out by eO in November 2023 and the findings of the routine bridge inspection by CDOT in September 2022. While CDOT’s inspection covered other bridge elements, including the concrete deck, columns, abutments, pier caps, protective coatings, slope protection, joints, bearings, wing walls, sidewalks, and railing, eO’s primary focus was on the six steel girders. This section details the findings, including defect locations, severity, and quantities. 4.2.1 Concrete Deck and Asphalt Overlay The concrete deck totals 16,945 square feet and shows moderate signs of degradation with heavy map cracking, efflorescence, and spalling. Transverse cracks with efflorescence, rust staining, and map cracking are widespread throughout the underside of the deck. Specific crack quantities with efflorescence and rust are outlined in the 2022 CDOT Structure Inspection and Inventory Report, indicating the need for a closer inspection and potential repairs. In conjunction with a new asphalt overlay, deck repair was performed on the bridge in 2018, which repaired several inspection and maintenance items. The wheel rutting in the overlay noted during the November 2023 inspection can lead to degradation of the deck over time if not properly maintained. A well-performing overlay system is the best defense for maintaining the integrity of the concrete deck underneath and extending its service life. The type of overlay is also important to enhancing the deck’s resistance to corrosion. Cementitious and non-cementitious wearing surfaces are available. The concrete deck issues noted will need to be monitored regularly to confirm the 2018 deck repair effort stopped or significantly slowed down the observed deterioration of the underside of the deck. If it is determined deck repairs need to be performed once again, the deck repairs would follow the typical protocol CDOT uses for this situation. In summary, this bridge shows significant signs of deterioration in all the areas typical of a bridge of this age. Although the concrete deck has recently undergone rehabilitation in 2018, a mill and overlay with deck repairs may be warranted once again. The exterior girders are also in need of replacement, which could coincide with the deck repairs. To preserve the life of the bearings and abutments, the expansion joints should be replaced. The bearings at the abutments need to be replaced, and bearings at the piers need additional rehab. The bridge’s concrete substructure shows significant signs of deterioration and in several locations requires immediate attention to prevent further overall damage or load carrying capacity. Figure 12. Deck Concrete Spall with Exposed Rebar 44 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 25 Infiltration of chloride ions into concrete is the most common cause of corrosion initiating in reinforcing steel. Chloride exposure is primarily through the application of deicing salts, such as magnesium chloride. Deck repair and patching or the installation of new membranes and overlays must begin by first identifying the extent of chloride contamination of the deck. Chloride testing consists of taking cores of the concrete deck and analyzing them for chlorides. Depending on the results of the testing, future deck rehabilitation may consist of the replacement of all chloride-contaminated concrete with sound concrete, along with the replacement of the membrane and wearing surface. It may also consist of the installation of a barrier-type overlay on the deck or full replacement of the deck. The test process may significantly impact traffic on the bridge when samples are taken. In addition, the potential deck rehabilitation effort will impact traffic on the bridge and may include full closer of the bridge to complete the repair work. Figure 13. Deck Concrete Spall with Exposed Rebar Depending on the chloride testing results of the concrete deck, a new overlay system along with localized deck repairs may be required, or if the contamination is widespread, a full deck replacement may be needed. Full deck replacement would provide the greatest mitigation for corrosion and degradation of the deck. However, it is also the most intrusive activity regarding construction requirements. The bridge would require full closure to replace the deck in its entirety. In the future, if it’s determined a full deck replacement is needed, it is recommended a full bridge replacement be considered, given the complicated nature of work involved with a full deck replacement. 4.2.2 Steel Girders The steel girders show varying degrees of corrosion. Exterior rolled steel wide flange girders (North exterior Girder A and South exterior Girder F) under each sidewalk show significant corrosion on the bottom flanges and lower webs (refer to Figure 14). Several locations along the girder also have severe localized corrosion in the top part of the web. On average, exterior girders show 20% section loss in the web. Some localized areas show up to 40% section loss. Both exterior girders show a visible sag with approximately 3 inches of downward displacement at mid-span locations (refer to Figure 15). 45 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 26 Compared to the exterior girders, the interior girders (B through E) have less corrosion. Surface corrosion and minor pitting are observed at these girders, especially at piers under the deck joints (refer to Figure 16). Girder ends at the abutments exhibited corrosion with negligible section loss. Figure 14. Significant Corrosion in Web and Top of Bottom Flange of North Exterior Girder A Figure 15. Girder F Sagging Near Mid-span 46 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 27 Figure 16. Typical Surface Corrosion of Interior Girder – Girder E South Face at Pier 4 4.2.3 Girder Stiffener and Tack Welds Tack welds, located at multiple stiffener locations for fit-up during the construction phase, have been inspected and classified based on crack propagation into self-arrested and not self-arrested (NSA) categories. Of particular concern are the NSA tack welds because their potential for crack migration into the girder base metal warrants focused attention. The extensive inspection performed by eO (2023) encompassed an estimated 3850 tack welds, revealing a distribution of 415 self-arrested cracks and 36 NSA cracks. Additionally, one specific instance of rivet shearing was identified. One stiffener in Girder B exhibited a noteworthy 1-inch out of plane deflection, emphasizing the necessity for a more in-depth structural evaluation at this stiffener location (refer to Figure 17). Stiffeners in exterior girders follow the same corrosion pattern as that of exterior girders as described in an earlier section. Notably, the vertical web bearing stiffener of Girder F at Abutment 6 has 100% section loss (2-inch diameter hole) at the bottom of the stiffener (refer to Figure 18). The bearing stiffeners of the interior plate girders, located at both the abutments and piers, are constructed using double back-to-back angles. They exhibit pack rust between the faying surfaces with a thickness of up to 1/2 inch. This rust has caused bowing in the stiffener legs at various points, as illustrated on Figure 19. While section loss in these regions is minimal, the accumulation of pack rust poses a potential concern over time. The continued presence of pack rust can induce separation between the angles, leading to further distortion of the angle shape. 47 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 28 Figure 17. Deflection of Stiffener at North Face of Girder B Figure 18. Section Loss in Base of Bearing Stiffener – Girder F at Abutment 6 48 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 29 Figure 19. Pack Rust Between Bearing Stiffeners of Interior Girder at Abutment 1 4.2.4 Steel Protective Coating The protective coating on the steel elements has failed in areas because of corrosion, indicating a need for prompt attention. Approximately 80% of coating has deteriorated. This deterioration contributes to the accelerated corrosion of the steel components, emphasizing the urgency of addressing protective coating issues. Figure 20 Failure of Protective Coating - Typical on All Steel Sections 49 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 30 4.2.5 Bearings The primary girder bearings display surface corrosion without measurable section loss, with some bearings surrounded by soil and debris specifically at Abutment 1 (refer to Figure 21). Loose anchor bolt nuts are observed at all bearings, and pin bolts are backing out at Bearings 1C, 1D, 3E, and 3F. Furthermore, certain fixed bearings on Abutment 6 exhibit surface corrosion, with the grout pad breaking up under several bearings. It is imperative to address these issues urgently to prevent further deterioration and unintended movement. Overall, the bearing condition is generally fair, with surface corrosion and identified problems with anchor bolts. The interior girder bearings, especially the rocker bearings at Abutment 1, are in the expansion position, which is opposite of what is expected in the colder weather conditions during the inspection in November. The abutment bearings on both Abutment 1 and Abutment 6 exhibit corrosion-related issues, including flaking and minor section loss. Debris accumulation around the rocker bearings on Abutment 1 is a concern because it can impede movement, trap moisture, and reduce the bearing assembly’s lifespan. Abutment 6 experiences surface corrosion on all bearings, with additional problems such as a broken grout pad on Girder 6B and deteriorating grout pads under Bearings 6C to 6E. Despite previous rehabilitation efforts in 2011, the grout pad below Bearing F is broken, with significant bearing loss. The fixed bearing (6F) is beginning to tip longitudinally, as shown on Figure 22. The bearing pedestal for Bearing 6A has a significant vertical crack stemming from the anchor bolts. This crack has propagated through the bearing pedestal and created a large section of delaminated concrete. Immediate attention is necessary to address these structural concerns. Figure 21. Rocker Bearing Covered in Dirt – Typical at Abutment 1 50 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 31 Figure 22. Movement of Bearing 6F at Abutment 6 Figure 23. Impending Spall in the Bearing Pedestal at Bearing 6A at Abutment 6 51 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 32 Figure 24. Loose Anchor Bolt Nuts – Typical at All Bearings 4.2.6 Diaphragms The steel diaphragms exhibit satisfactory overall condition, except for surface corrosion identified in the C-Channel diaphragms at the piers. Notably, the C-Channel diaphragms between the exterior and interior girders at piers show corrosion with 10% to 30% section loss of the webs. Figure 25. Surface Corrosion of C-Channel Diaphragms – Typical at All Diaphragms 52 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 33 4.2.7 Pier Caps Pier caps exhibit moderate to heavy water staining, light scaling, delamination, and various severity of cracks. Specific issues include a 4-square-foot spall with exposed, corroded rebar on Pier 2, rear face under Girder E. Pier 3 cap shows delamination and cracks with efflorescence, while Pier 4 cap displays delamination, shallow spalls, and horizontal and diagonal cracking below Bay 3C. Pier 5 cap is starting to delaminate on the right side under Bay 4D. Figure 26. Exposed Corroded Rebar on Pier Cap at Pier 2 Figure 27. Light Scale Cracking at Pier Cap – Typical at All Pier Caps 53 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 34 4.2.8 Abutments Abutment 1 is covered in debris from previous rehabilitation projects and possibly from an effort to cover the high-pressure gas line. A portion of the backwall appears to have been removed approximately 3 feet from the top during previous construction projects, then recasted to a thinner section thickness. Vertical rebars along the front face of the existing backwall have been cut and are exposed at some locations. Abutment 6 has some light scale, delamination, and water staining. Figure 28. A Portion of Abutment 1 Backwall Was Removed During Previous Construction 54 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 35 Figure 29. Light Scale, Delamination and Water Staining at Abutment 6 4.2.9 Expansion Joints Observing inadequate joint sealing at Abutment 6 raises concerns about the bridge's structural performance. Despite the presence of fixed bearings at this abutment, notable movement of the bridge has been observed through the existing conditions of the bearings, as shown on Figure 22 (Section 4.2.5). One plausible explanation is the potential impact of the partially buried rocker bearings at Abutment 1. The bearings at Abutment 1 were intended to absorb thermal movements of the bridge, whereas the bearings at Abutment 6 were intended to remain stationary on the abutment seat. It is possible the partially buried bearings at Abutment 1 may be restricting the performance of the rocker bearings, thereby contributing to unintentional movement at the fixed end of Abutment 6. Another factor under consideration is the relocation of the expansion joint from the backwall of Abutment 1 completed in late 2022, which may be contributing to the observed issues. A comprehensive analysis is needed to identify the root cause of the unexpected movement behavior of the bridge bearings and determine the most effective remedial measures. 55 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 36 In addition to the structural concerns, the inadequacy of the joint seal at Abutment 6 has exacerbated the situation. Water infiltration from the pavement to the abutment has been observed, resulting in deterioration of the concrete below. If left unaddressed, this issue could lead to significant deterioration of the concrete and bearings in the future. Figure 30. Inadequate Joint Seal at Abutment 6 56 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 37 4.2.10 Slope Protection According to the CDOT inspection report for 2022, maintenance personnel in Aspen have reported the need to annually adjust or reposition the timber wall supporting the bike path to a vertical orientation at Abutment 1. This recurring issue has prompted the City to initiate a rehabilitation project aimed at addressing the structural concerns associated with the timber wall. Mitigation of the retaining wall and bike path helps the continued protection of Abutment 1. Figure 31. Movement of Timber Retaining Wall at Abutment 1 4.3 Rehabilitation Recommendations The bridge inspections (CDOT 2022; eO 2023) revealed significant deterioration in various elements that require immediate attention to enhance the long-term durability, functionality, and safety of the bridge. However, it is crucial for the owner, users, and local community to understand rehabilitation is a substantial effort. Further, while rehabilitation can address certain issues, it may not be a cure-all for every issue linked to the bridge. The following work is highly recommended to rehabilitate the bridge: 1. Bearing Replacement and Maintenance: It is important to completely replace the bearings at Abutments 1 and 6. This measure ensures the restoration of proper load distribution and minimizes structural stress from thermal movements of the bridge. Cleaning and repainting all pier bearings prevents further corrosion and can help extend the lifespan. The replacement or insertion of missing nuts, pins, and bolts, along with grout pad replacement where necessary, enhances the overall stability and performance of the bridge. And finally, cleaning the bearing seats is an easy way to prevent moisture buildup and debris from preventing the bearings to function as designed. 57 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 38 2. New Bearing Pedestal at Abutment 6: Replacing the cracked north side exterior girder bearing pedestal at Abutment 6 is crucial to ensure the bridge’s stability and load-carrying capacity of the sidewalk. 3. Exterior Girder Replacement: The extensive section loss in both exterior girders warrants replacement. This action not only restores the load-bearing capacity of the bridge but also ensures the elimination of compromised elements, safeguarding against potential structural failures. Replacing the exterior girders would also trigger the replacement of the sidewalks above and potentially the bridge railing. 4. Steel Protective Coating Rehabilitation: A durable high-performance coating is recommended to protect the steel elements from corrosion. It is apparent the existing paint is at or near its design life for the structure. The existing protective coating has failed on multiple bridge elements. Reapplication of protective paint is essential to prevent further corrosion. Protective paint provides a barrier against environmental factors, such as corrosion and preserves the integrity of the steel components. 5. Tack Weld Removal and Monitoring: Removal of cracked tack welds, especially those not considered self-arrested, is crucial for eliminating potential weak points in the structure. If funds allow, removing all tack welds from the structure avoids future close monitoring at higher frequencies. If it is not economically viable to remove all tack welds, it is recommended for continuous monitoring of the welds to be carried out during routine inspections to ensure timely identification and management of any emerging issues. 6. Concrete Deck and Asphalt Overlay: Addressing spalls, cracks, and delamination through concrete deck repairs is vital for maintaining the bridge’s overall long term structural integrity. The initial step would be to determine the condition of the deck through chloride testing to determine the extents of repair required. Assuming a new overlay and deck repair activities, the Contractor would chain drag the deck and mark locations that are delaminated. These locations would then receive a Class 2 or Class 3 deck repair depending on the severity of the degradation. Then a thin polyester polymer concrete (PPC) overlay would be constructed over the repaired deck to provide a barrier against chloride infusion. The new PPC overlay would replace the current asphalt and membrane system as a more effective overlay system for a compromised deck to extend the service life. NOTE: If the chloride testing indicates extensive infiltration of chloride ions in the deck, a deck replacement is likely needed. Performing a deck replacement at CCB is extremely difficult if traffic needs to be maintained during construction. Further, the existing 6.5-inch deck thickness is atypical of current design code minimum deck thickness. The remaining superstructure and substructure are not currently designed for additional loading to support a thicker deck. Therefore, if a deck replacement is warranted, a full bridge replacement is recommended, as described in Section 5. 7. Pier Cap Repairs: Repairing the observed spalls and cracks on the pier substructure elements will also prevent further degradation of the components and improve the overall long term durability of the bridge. Leaving 58 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 39 the defects unchecked or repaired increases the potential for water infiltration and subsequent corrosion of the steel reinforcement. 8. Joint Seal Replacement: The replacement or addition of open-joint seals at all sidewalks and joints at all piers and Abutment 6 is essential to prevent water infiltration. This rehabilitation mitigates the risk of water-induced damage, including delamination, preserving the structural components. 9. Bridge Rail Replacement: The current bridge rails do not meet AASHTO Manual for Assessing Safety Hardware (MASH) (AASHTO 2016) criteria. Replacing the bridge rails with MASH compliant bridge rails will further improve the safety and sufficiency rating for the bridge. While typically a bridge rail replacement can be problematic on older bridge decks, the replacement of the exterior girders facilitates replacement of the bridge rails by rebuilding the deck overhangs to accommodate the design loads associated with the new railings at the same time. The recommended rehabilitation measures are an attempt to maintain structural integrity and safety while improving the long-term durability of the bridge. Although implementation of these measures will help provide a prolonged service life, it is challenging to estimate how much service life will be added to the bridge. It is important to acknowledge these interventions primarily focus on preventing further deterioration of the bridge rather than providing substantial improvements in the bridge’s load-carrying capacity. Regular monitoring and follow-up inspections will be crucial to evaluate the effectiveness of these rehabilitation measures and promptly address emerging issues as they appear. Rehabilitation measures discussed in this section are intended to improve the service life of the bridge by addressing the structure's immediate maintenance needs. It is important to note the following issues would not be mitigated as part of the proposed rehabilitation: a. Increasing the Load Rating of the Bridge: The proposed rehabilitation measures do not address the challenge of increasing the load rating of the bridge deck and girders to meet current design standards. The existing bridge was designed using an AASHTO live load of H20-S16-44. Updating the structure to adhere to the current AASHTO and CDOT's Live Load standard (BDM 2023) would require extensive rehabilitation and strengthening, including structural evaluation of the substructure, which has its own unique limitations. b. Significantly Reducing Current Maintenance Demands: The proposed rehabilitation measures do not substantially reduce the ongoing maintenance demands of the bridge. Despite regular maintenance efforts over the past three decades, the bridge's condition rating has consistently remained at ”Fair.” This extended duration of “Fair” condition implies persistent structural and maintenance concerns, suggesting the proposed measures may not result in a notable decrease in routine maintenance requirements. c. Removing the "Functionally Obsolete" Categorization: The proposed rehabilitation measures do not address the challenge of removing the bridge from the "functionally obsolete" (FO) categorization. The current functional obsolescence is attributed to the inadequate roadway width, which cannot accommodate the current traffic volume. This FO status contributes to a reduced sufficiency rating. Despite proposed rehabilitation interventions, the bridge will retain its FO status. Additionally, these rehabilitation measures do not improve other deficiencies of the bridge, such as the limited viable detours. 59 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 40 4.4 Sufficiency Rating Calculation after Proposed Rehabilitation The sufficiency rating computed in this section considers the rehabilitation interventions outlined in the preceding section. It is assumed the superstructure's condition rating increases from the existing 5 to 6, while the deck condition rating remains at 6. Providing a new wearing surface to the deck will help protect the deck but will not change the condition of the underside of deck. The latest condition rating of the deck was based on the underside of deck because the top was not inspectable. Replacing the bridge rails eliminates the “special reductions” applied in the sufficiency rating. All other parameters remain unaffected by the proposed rehabilitation efforts. After factoring in the condition rating increase from the proposed rehabilitation, the increase in sufficiency rating was found to be modest from 50.3 to 64.7 (refer to Appendix C for sufficiency rating calculations), which, in the broader context of the Highway Bridge Replacement and Rehabilitation Program criteria, does not constitute a significant improvement. 4.5 Construction Phasing The proposed construction phasing for the bridge's rehabilitation considers the critical need to minimize disruptions to traffic flow to and from Aspen. Recognizing the available substandard large vehicle access and inconvenient alignment of the required detour roadway, a total closure of the bridge during rehabilitation is deemed impractical. Instead, a phased approach is adopted, allowing for partial opening of the bridge to traffic. This strategy involves completing construction on one section of the bridge before shifting traffic to the other side to help eliminate significant traffic disruptions. One temporary lane, configured with a minimum width of 11 feet is proposed during construction, enabling anticipated speeds of up to 15 to 20 miles per hour (mph) for one direction of travel. Continuous maintenance of traffic using either a signalized alternating lane or a single lane across the bridge in one direction paired with a companion detour in the other direction would be required to complete the proposed rehab activities. Refer to Section 6, Traffic Impacts, for further information on maintenance of traffic options and associated impacts during construction. Bridge rehabilitation is recommended for nine key bridge elements. While the rehabilitation aims to extend the service life of the bridge, three specific issues cannot be remedied by a rehabilitation, including accommodating heavier vehicle loadings, reducing maintenance needs, and eliminating the limited functionality of the narrow roadway width. The sufficiency rating is not greatly increased by the rehabilitation because of other constraints on the bridge, specifically the vehicle travelway width. The validity of the rehabilitation to extending the bridge service life is also dependent on factors such as routine maintenance. 60 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 41 Figure 32. Rehab Construction Phasing – Phase 1 (Looking East) Figure 33. Rehab Construction Phasing – Phase 2 (Looking East) In the proposed construction phasing, Phase 1 will involve the replacement of the exterior girders on the southern side. This includes the replacement of bearings for Girders D, E, and F at both abutments. Additionally, all other bearings on Girders D, E, and F will be cleaned, the bearing grout pads will be regrouted where necessary, and any instances of deck spalling will be patched. The subsequent phase will mirror this rehabilitation process, focusing on the northern side of the bridge. Additionally, Phase 2 will involve the replacement of Bearing Pedestal for Girder A at Abutment 6. Larger vehicles, such as snow cats and plows, also use the bridge to access the ski resorts and Independence Pass. Traditional snowplows and smaller snowcats can travel over the bridge during construction, but larger snowcats (up to 19.5 feet wide with the blade) cannot be accommodated during the rehabilitation because of spatial constraints. Pedestrian access can be maintained throughout rehabilitation work. Specifically, work will be carried out on the exterior girder supporting the south sidewalk during one phase, while the exterior girder supporting the north sidewalk will be the focus in another phase. This phased approach ensures pedestrians can access the bridge throughout the construction process. Phasing utilities during bridge rehabilitation involves strategic planning to determine the most effective sequencing of construction activities. Utilities directly supported on the bridge will require permanent or 61 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 42 temporary relocation while bridge rehabilitation activities are performed. The construction phasing provided in Appendix H, completing the south side of the bridge first to accommodate utility relocation before rehabilitation on the north side, is the recommended sequence. Relocation will require installation of approximately 10 new conduits, using utility boring under SH 82 at the bridge approaches to reroute conduits on the south side of the bridge. 4.6 Schedule The rehabilitation of the SH 82 Bridge is proposed to be conducted within a restricted timeframe, dictated by weather conditions and the need to adapt to various community events in Aspen and the surrounding areas. The phased rehabilitation plan will maintain traffic in one lane across the bridge and use a companion detour carrying another lane allowing traffic into Aspen during morning peak hours and away from Aspen during evening peak hours. Anticipating a construction duration of 4 to 6 months per phase, the proposed schedule aims to complete one phase per year and the entire rehabilitation to be completed within 2 years. Table 3. Rehabilitation Schedule Phasing Total Construction Duration SH 82 Impact Duration Maintenance of Traffic Duration Phase 1 4-6 months 4-6 months 4-5 months Phase 2 4-6 months 4-6 months 4-5 months 4.7 Cost Estimate The preliminary bridge cost estimates outlined in this feasibility study are initial approximations and should be viewed as a general indicator of cost rather than conclusive figures. The primary purpose of this cost estimate is to give a general “ballpark” idea of costs associated with the prescribed rehabilitation measures. The preliminary cost estimate, which encompasses construction costs and a high-level assessment of costs to relocate utilities during construction, is $5,900,000. This does not represent a full project cost because project costs for mobilization, traffic control, site civil work for roadway approaches, and any other non-structural items are not included. Section 7 discusses and calculates the overall project costs associated with the rehabilitation option. Refer to Appendix D for the cost estimate for the proposed rehab activities. 4.8 Summary and Conclusions Recent inspections have revealed significant concerns about the CCB, with girders showing varying signs of deterioration, the underside of deck showing signs of distress, and other localized structural issues. The sufficiency rating is currently at 50.3. Despite substantial rehabilitation efforts in 2011 and 2018, the bridge only achieved a “Fair” rating. A recent hands-on inspection confirmed the assigned “Fair” condition with a superstructure condition rating (NBI Item 59) of 5. The field inspection highlighted various issues, particularly in the underside of concrete deck and steel girders. The underside of concrete deck exhibits signs of degradation and widespread surface cracking. Bridge rehabilitation will significantly affect local traffic for the duration of the work. A single traffic lane is provided during each phase of the construction. 62 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 43 Steel girders display varying degrees of corrosion, with exterior girders showing significant corrosion and sag. Numerous tack welds and girder stiffeners exhibit cracks, and protective coatings on steel elements have failed, contributing to accelerated corrosion. Given the significant deterioration, a comprehensive rehabilitation plan is essential. Proposed measures include bearing replacement, exterior girder replacement, protective coating rehabilitation, tack weld removal, pier column and cap repairs, joint seal replacement, and bridge rail replacement. While these measures aim to slow down and prevent further deterioration, they are not expected to bring improvements in the load-carrying capacity of the bridge or significantly extend the service life of the bridge. Proposed rehabilitation plans are provided in Appendix H. Regular monitoring will be crucial to assess the performance and effectiveness of the proposed rehabilitation measures over the life of the bridge. 5. Bridge Replacement Feasibility This section summarizes the feasibility of bridge replacement. 5.1 Bridge Width Alternatives Two alternatives were considered for the feasibility of replacing the existing bridge as requested by the City. The first alternative considers that two lanes are provided on the new bridge, the southern sidewalk is removed, and the northern sidewalk is replaced. The second alternative considers that the bridge be widened to accommodate three lanes and a sidewalk on the northern side of the bridge. In both alternatives, the northern sidewalk is considered to be replaced with a 10-foot-wide sidewalk, which is understood to be the preference of the City Parks Department because it will accommodate future demands as a trail. The three-lane alternative would provide the flexibility to have one lane designated for transit (bus or light rail) in the future. The presence of a transit lane on the three-lane alternative would result in increased live load effects on the bridge and would require increased superstructure depths. When determining approximate superstructure depths in Section 5.2, the AASHTO span-to-depth ratios are amplified by a factor of 1.30. The previous SH 82 Reversible Lane Feasibility Study (SGM 2008) has already documented the challenges and insufficiencies of trying to add a third lane to the existing bridge. Therefore, only a bridge replacement is considered for a three-lane bridge. The two-lane alternative aims to maintain a similar width to the existing bridge. However, as discussed in Section 5.3, the space required to provide temporary lanes for access during construction is limited and requires an overall width of 48 feet 10 inches for the two-lane alternative. This is only slightly less than the 52 feet required for the three-lane alternative. The proposed rehabilitation interventions would result in a modest increase to the sufficiency rating. The proposed measures would not significantly improve the bridge condition to a level where total replacement is not deemed necessary. Challenges such as increasing the load rating, reducing inspection/maintenance demands, and improving the roadway width will not be addressed by the proposed rehabilitation, suggesting possible replacement of the bridge may be necessary to address these issues. 63 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 44 5.2 Structure Type The following subsection describe the CCB structure. 5.2.1 Span Configurations The existing bridge consists of five spans for a total length of 420 feet from bearing to bearing. The end spans have lengths of 75 feet, and the center three spans have lengths of 90 feet. The bridge passes over a pedestrian/bike trail at the west abutment, Power Plant Road in two locations, Castle Creek, and Harbour Lane near the east abutment. Additionally, near the piers under the bridge are fuel pumps belonging to the City at their maintenance building, and there are homes toward the east abutment along Harbour Lane. Figure 34. Site Overview The bridge replacement alternatives considered these constraints under the bridge when determining possible pier locations. Per the City, piers can be anywhere within the parking lot of the Aspen Streets Department building if there are no impacts to the fuel station or storage tanks. The existing bridge has a pier within Castle Creek. It is recommended this pier is removed and not replaced to avoid further impacts to the waterway and permitting issues. With that, piers at the east side of the bridge can be placed on the east bank of Castle Creek, west of Harbour Lane, or along the slope east of Harbour Lane. Reducing the number of piers subsequently reduces construction cost and schedule. Because of the height of superstructure above the valley, the piers are anticipated to be costly because larger columns and foundation elements will be required. However, the cost savings realized from eliminating piers needs to be compared against the additional costs of a deeper superstructure to achieve the longer spans. 64 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 45 Additional superstructure costs arise from requiring more material for deeper members, and the extra depth may also require the profile on the bridge to be raised. To maintain traffic on SH 82 during construction, the existing bridge will need to remain partially open while portions of the new bridge are constructed. To support the existing roadway, the existing bridge piers need to remain in place while the new bridge superstructure is constructed over the existing piers. This means that if the new bridge superstructure is deeper than the existing, the profile of the bridge would need to be raised. Raising the profile of the bridge would place the new bridge deck above the existing deck and require extensive reconstruction of the roadway approaches to tie into the existing roadway profile. With the proximity of homes near the bridge and roadway at the east abutment, the cost of construction and ROW impacts would be significantly increased; therefore, a profile raise is not considered feasible. This limit to the structure depth eliminated a one span and two span bridge from consideration because the span lengths would result in significantly deeper superstructures. Three- and four-span layouts were considered; their feasibility depends on the type of superstructure and whether a profile raise would be required. For more information, refer to Section 5.2.2. When laying out preliminary options for the three- and four-span pier locations, the limits set forth by CDOT BDM Section 5.5.1.9 (2023a) regarding the shipping and handling of girders were considered. This section limits the maximum length of a single girder segment to 154 feet and the maximum weight to 240 pounds-force (kips) (240,000 pounds). This only impacts the alternatives using precast concrete or steel because these members are prefabricated and shipped to the site for erection. Figure 35. Three-span Configuration 65 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 46 Figure 36. Four-span Configuration The four-span configuration provided on Figure 36is presented in the conceptual drawings and used for cost estimates for both the two- and three-lane alternatives because it capable of keeping the structure depths approximately the same as the existing bridge. The three-span layout is possible in terms of structure depth and shipping restrictions if a steel girder superstructure were used, but because of construction restraints (discussed in Section 5.2.2), it is not feasible, and the three-span bridge is not considered further. 5.2.2 Materials The following subsections describe the materials reviewed for the feasibility study. 5.2.2.1 Precast Concrete Precast concrete girders are fabricated at two precast facilities in the Denver Metro area and surrounding states. These girders have their concrete cast in form beds around pretensioned high-strength steel strands. When the concrete reaches a desired compressive strength, the strands are cut, and they compress the girder to achieve its capacity. The girders are then stored at the precast facility until they are ready to be shipped to the site for erection. Precast concrete girders are flexible when it comes to span capabilities because they can take various shapes and depths. As discussed in the previous subsection, the maximum length is 154 feet, and the maximum weight is 240 kips. In situations where these shipping limits start to govern (for larger depth girders), several girder segments can be spliced together using post-tensioned strands at the bridge site to achieve longer spans. The four-span bridge configuration provides the best opportunity to control span lengths for a shallower structure depth that will accommodate traditional phased construction. 66 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 47 However, once the precast girders arrive onsite, they would need to be set into place using cranes. This can be done in several ways for a standard project. Cranes could be placed on the existing bridge, and the girders can be picked from trucks to swing into position. However, because of the limited space available for temporary lanes, this is not a viable option because SH 82 would require a full closure for the girders to be erected (assuming sufficient space for the cranes to operate from the existing bridge). For this operation, the girders would need to travel across the bridge using temporary lanes, and the cranes would need to mobilize into position. After setting a girder, the cranes would need to mobilize off the bridge and repeat this process, resulting in lengthy periods of full closures of SH 82, which is not feasible. Another option for setting the girders would be to construct a large lattice crane beside the existing bridge to lift the girders into place. This becomes challenging for various reasons, including the facilities under the bridge and the weight of the girders. With Power Plant Road, Castle Creek, and Harbour Lane under the bridge, the locations where a large crane could be placed is limited. A crane would most likely need to be constructed south of the bridge, in/near the Aspen Streets Department parking lot. Placing the girders at the western side of the bridge would not be as difficult, but the girders at the eastern side of the bridge would be challenging. This would require a large radius for the crane to reach, and it would be carrying girders over the facilities under the bridge and near residential structures by the east abutment. This would require closures of the roads under the bridge, and safety measures would be required to protect the residential structures adjacent to the bridge. Compounding on this problem is the weight of precast girders because they are typically heavier than other alternatives such as steel. With the long reach required, as the girder becomes heavier, the size would be required also increases. Because of this, erection becomes problematic, and the precast concrete girders would not be feasible for this location. 5.2.2.2 Steel Steel girders are like precast girders because they are fabricated offsite, shipped, and erected via the use of cranes. The same concerns regarding the challenging erection of the precast concrete girders are present for the steel girders; however, steel girder members are typically lighter (50% to 60% less) than precast concrete members of similar lengths. Steel girder construction requires the splicing of several girder segments and would necessitate additional falsework to be constructed, so the splice connections can be installed. The use of these splice connections can be helpful in reducing the weight of the girder segments being lifted by a crane. These spliced connections are common practice for steel construction; whereas, spliced precast girder segments is not as common in Colorado. These lighter weights of girders make the steel erection a more practical operation but would still be challenging and require a large lattice crane to be used. It is estimated a 250- to 300-ton crane would be required for the erection of the outer spans. The lattice boom would need to be assembled in the roadway, which would require a lane closure. For the inner spans, the use of a 250-ton telescopic crawler crane would need to be transported, assembled, and positioned below on the south side of the structure. Both crane sizes and locations are shown on Figure 37, identifying the lifting radius from each crane. SH 82 would require full closure at night when the center span girders would need to be offloaded from the existing bridge and erected. 67 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 48 Figure 37. Approximate Crane Layout Needed to Erect Steel Girders Overall, the steel girders are a potential option for the replacement of the existing bridge; however, the erection of the girders may be a limiting factor for the reasons stated in this subsection. 5.2.2.3 Cast-in-place Concrete Cast-in-place concrete girders are constructed onsite and require falsework to be constructed to form the concrete. After the concrete has reached a desired strength, high-strength steel strands are run through ducts placed inside the concrete girder and tensioned. These post-tensioned strands compress the girder to provide its capacity, similar to the precast pretensioned concrete girders previously discussed. The benefit of the cast-in-place concrete girders are that heavy girder segments are not lifted into place. However, falsework would need to be constructed along the entire length of the bridge to form and support the concrete throughout the duration of construction. Before the post-tensioning, the concrete is not capable of spanning between the abutments and piers and requires external support. The falsework would need to be designed to provide openings that allow for access to Power Plant Road, Castle Creek, and Harbour Lane under the bridge, similar to Figure 38 where bays are open for traffic flow. While the falsework is constructed, smaller cranes and temporary closures/lane shifts of the facilities under the bridge would be required. However, it is anticipated this would be less impactful than the steel girder erection operations previously described. 68 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 49 Figure 38. Example Falsework Photo for Cast-in-place Concrete Construction A cast-in-place concrete superstructure with post-tensioning would pose some challenges if any future widening of the structure is explored. A typical widening project would remove the overhangs such that additional girders can be added to expand the deck. Because of the post-tensioning, the concrete is in a stressed condition that prevents the concrete from cracking, providing it strength against external loads. Removing the overhang would change the section properties of exterior girders significantly and could result in damage to the superstructure. Steel or precast concrete girder systems can be widened in a simpler manner because the overhangs are not stressed by post-tensioned strands. Because of this, the three-lane alternative would be beneficial should the cast-in-place concrete option be used because it could accommodate future traffic and transit demands. The cast-in-place concrete alternative is a viable option for replacement of the existing bridge. While the erection concerns are eliminated, falsework construction under the bridge would be required. This alternative is shown in the attached conceptual drawings because it is anticipated to have the best constructability. 5.2.2.4 Structure Depth Approximate depths of the superstructure were determined using the span-to-depth ratios defined by AASHTO Table 2.5.2.6.3-1 (AASHTO 2020). This table provides guidance regarding traditional minimum depths of superstructures that depend on the type of construction and span lengths. The resulting depths from this table are typically conservative when compared with final design member depths determined from detailed calculations that follow the AASHTO LRFD specifications (2020). As discussed in Section 5.1, the span-to-depth ratios for the three-lane alternative are increased by 30% to account for additional loading from the potential future light rail transit on the bridge. Table 44 presents the approximate superstructure depths, girder height, plus deck thickness for the two- and three-lane alternatives. Not feasible (NF) is provided for alternatives where a profile raise would be required and the alternative is not feasible. 69 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 50 Table 4. Superstructure Depths Superstructure Type Two-lane Three-lane Three-span Four-span Three-span Four-span Cast-in-place Concrete 6.40 feet (NF) 5.08 feet 8.32 feet (NF) 5.92 feet Steel 5.08 feet 5.08 feet 6.66 feet (NF) 5.08 feet As presented in Table 4, the cast-in-place concrete alternatives would require profile raises for the three-span configuration provided on Figure 35. Therefore, the cast-in-place concrete superstructure type is only recommended for the four-span configuration shown on Figure 36. For steel, a profile raise is only required for the three-lane alternative when the three-span configuration is used. With that, the conceptual drawings in Appendices I and J provide the four-span configuration with a cast-in-place concrete superstructure. Figure 39 and Figure 40 present the typical section for the cast-in-place concrete superstructure for the two- and three-lane alternatives. This structure type is anticipated to provide the best constructability and would not require a profile raise. The other options presented in this report may also be reasonable but would require further analysis not in the current scope. Figure 39. Two-lane Alternative Cast-in-place Concrete Typical Section 70 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 51 Figure 40. Three-lane Alternative Cast-in-place Concrete Typical Section 5.3 Construction Phasing This section details construction phasing possibilities for both the two- and three-lane alternatives. 5.3.1 Service During Construction With SH 82 being the primary access in and out of Aspen, constructing the replacement bridge in phases is recommended. This would allow for portions of the existing bridge to remain open and provide access to vehicular and pedestrian traffic while the new bridge is constructed. As portions of the new bridge are completed, traffic can be shifted off the existing bridge and onto the new bridge. Availability of vehicular lanes and a pedestrian walkway across the bridge during construction will be dependent on the bridge phasing, which is further discussed in Section 5.3.2 for each option evaluated. All phasing options considered in this report rely on the existing bridge to carry traffic in a partial state throughout the duration of construction. Full demolition and reconstruction of the bridge is only available as an option if a new detour route is built for all traffic to shift away from the existing bridge site and all impacts to travelers are eliminated. This is discussed further in Section 6 for traffic impacts. The following is a list of constraints and assumptions considered when developing a bridge phasing plan: - SH 82 traffic movement is paramount. Because a full bridge closure is not an option, bridge construction needs to be traditionally phased with temporary lanes. - 5-foot wide (minimum) pedestrian access is required during all phases of construction either on or below the bridge. For more details, refer to Section 5.3.2. Precast concrete, steel, and cast-in-place concrete were evaluated for structure type feasibility. The steep terrain and facilities under the bridge limit the space for large cranes, eliminating the ability to use precast concrete. Crane placement for steel requires closures of Power Plant Road. Therefore, only cast-in-place concrete is advanced further because it provides the best constructability and limits impacts to the SH 82 profile. 71 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 52 - Traditional snowplows and smaller snowcats can travel over the bridge during construction, but larger snowcats (up to 19.5 feet wide with the blade) cannot be accommodated because of spatial constraints. - The new bridge footprint is ideally inside the ROW limits because additional ROW acquisition is cost prohibitive. - Temporary barriers need to be pinned to the deck to provide space for 11-foot wide lanes with 2-foot shoulders during maintenance of traffic, which ultimately controls the width of each construction phase. - Short term closures on SH 82 and Power Plant Road will be required to accommodate bridge construction. A protective canopy can be installed to protect traveling public below the bridge. - Utility relocations are required before demolition of the north side of the bridge. - New pier construction can occur before the existing bridge is demolished. - An “overbuild” is when the new bridge is built wider than the required final condition and is often used to accommodate traffic patterns during construction phasing. A bridge overbuild to the north and south was investigated because it would allow for uninterrupted traffic flow on SH 82. However, spatial constraints at the bridge site prevent an overbuild. Any significant ROW acquisition would be very costly and ultimately eliminate an overbuild as a feasible option (refer to Figure 41). Figure 41. Bridge Footprint Required to Overbuild New Bridge Outside of Existing, Deemed Not Feasible 72 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 53 5.3.2 Phasing Options Traditional construction phasing options are provided in the following subsections. While several phasing options were initially considered, the four options presented were advanced for further consideration. Table 5. Phasing Options Advanced for Consideration Phasing Option Opportunity Two-lane Replace Replicates the existing condition for a comparison. Three-lane Centered Provides the least impact to the bridge site. Three-lane Faster Provides the shortest phased construction duration. Three-lane Shifted Provides the least impact to the traveling public (vehicular and pedestrian). 5.3.2.1 Two-lane Replace The two-lane alternative aims to replace the bridge with a new bridge of similar width and footprint. Only one option was considered for this alternative because the only other option to maintain the same footprint of the bridge would be to fully close and replace the existing bridge. The bridge phasing considered for the two-lane alternative allows for the front face of the northern sidewalk to remain in approximately the same location as the existing. The southern edge of deck would move to the south, which would require some roadway reconstruction to tie into the adjacent roadway segments; however, it would be minimal. For this option, four phases of construction would be required to replace the bridge, but it allows for a single lane of traffic to be open during all phases of construction. For more details, refer to the two-lane diagrams provided in Appendix G. The final width of the two-lane bridge is 8 feet10 inches wider than the existing bridge while providing sufficient room for the 10-foot sidewalk at the northern edge of deck and two 11-foot lanes. The additional width is a result of the space required to fit the temporary travel ways at various phases as described in Section 5.3.1. While wider than the existing bridge, no ROW acquisitions are anticipated because the footprint of the bridge deck is within the ROW limits from a previous survey provided to Jacobs by the City (City of Aspen n.d.). 73 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 54 Figure 42. Two-lane Replace, Bridge Footprint 5.3.2.2 Three-lane Centered This option is essentially the same as that described for the two-lane alternative, and all previous discussion are applicable to this option. Similar to the two-lane phasing, this results in the northern face of sidewalk remaining in approximately the same location as that of the existing bridge. Minimal roadway work would be required to tie into adjacent roadway segments. The only difference is the exterior segments constructed during Phases 1 and 2 are wider to accommodate the additional width needed for the third lane. This final configuration can accommodate a 10-foot sidewalk, three 11-foot lanes, and two 3-foot shoulders. While the bridge is wider, no ROW acquisitions are anticipated because the bridge footprint is within the ROW limits. For more details, refer to the Three-lane Centered diagrams provided in Appendix G. 74 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 55 Figure 43. Three-lane Centered, Bridge Footprint 5.3.2.3 Three-lane Faster This option proposes the removal of the exterior segments of the existing bridge during Phase 1 of construction. This allows for sufficient width to be constructed such that two temporary lanes can be provided earlier, making the single traffic lane only required for one phase. However, pedestrians would need to be rerouted under the bridge because there would not be sufficient width to accommodate pedestrian access on the bridge during any phase. For more details, refer to the Three-lane Faster diagrams provided in Appendix G. Phase 1 of construction would require SH 82 to be reduced to a single lane, so the exterior segments of the existing bridge can be demolished and replaced. Refer to Section 6 Traffic Impacts for further information on the traffic impacts of using only one lane during construction. Once the exterior segments of the new bridge are complete, SH 82 eastbound and westbound traffic can be split and carried by the new bridge segments. The remaining center segment of the bridge could then be removed and replaced. Once the center segment is complete, closure pours can be placed to connect the three segments of the new bridge. The sidewalk at the north can be constructed, and the SH 82 lanes can be placed on the new bridge. This option requires the new bridge to shift to the south by approximately 3 feet 8 inches beyond the ROW limit and would require ROW acquisition. Trees in this region may also be impacted and require removal. 75 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 56 As presented on Figure 44, the southern edge of the bridge is nearly above the residential structure on Harbour Lane. Additional care would be required during pier and superstructure construction to protect this residence. Figure 44. Three-lane Faster, Bridge Footprint 5.3.2.4 Three-lane Shifted The intention of this option is to maintain two lanes on the bridge during all phases of construction. To accomplish this, most of the existing bridge needs to remain in place to be able to carry two temporary lanes while the first portion of the new bridge is constructed. The southern exterior segment of the new bridge is proposed to be constructed first because this will cause the bridge to be shifted to the south, similar to Three-Lane Faster, and will avoid conflicts with the residential structures to the north. For more details, refer to the Three-lane Shifted diagrams presented in Appendix G. Because of the bridge shifting to the south, the face of the northern sidewalk does not align with the existing sidewalk face for this option. This would require reconstruction of the adjacent roadway segments on both sides of the roadway. Like the Faster option, the southern edge of the deck is beyond the ROW limit by approximately 4 feet 6 inches, and trees in this area would be impacted. As shown on Figure 45, the house on Harbour Lane is nearly under the bridge and would require care during construction to protect the residence. 76 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 57 Figure 45. Three-lane Shifted, South, Bridge Footprint Figure 46 presents the resulting Three-Lane Shifted bridge footprint. The result is the bridge shifting to the north and being in proximity to the residential structures near the east abutment. Additionally, abutment and wingwall construction would be very close to the structures and is not recommended. Because of this, shifting the bridge to the north is not considered feasible. Figure 46. Three-lane Shifted, North, Bridge Footprint 77 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 58 A variation of the Shifted option was considered to accommodate pedestrians in all phases. Adding a 5- foot pedestrian path shifts the entire bridge further south, placing it over the residential structure and requiring almost 12 feet of additional ROW. Because of these impacts to the residential structure and the significant increase in ROW acquisitions, accommodating pedestrians across the CCB in all phases of the Shifted option is not considered feasible. 5.3.2.5 Phasing Option Summary Table 6 summarizes the impacts and constraints of the four phasing options described in this report. As discussed, only one option was considered for the two-lane alternative, and the phasing described is presented on the conceptual drawings. For the three-lane alternative, Centered is anticipated to be the least impactful, even though a single lane of traffic is required for two construction phases. This option eliminates the need to shift the bridge, reduces the amount of roadway reconstruction, does not require ROW acquisitions, and eliminates the risk associated with constructing the bridge above the residential structure on Harbour Lane. Table 6. Phasing Option Impact Summary Phasing Option Impacts Single Traffic Lane No Pedestrian Access on the Bridge ROW Acquisition Construction Nearby/Above Residential Structures Adjacent Roadway Realignment Two-lane Replace High Medium Low Medium Medium Three-lane Centered High Medium Low Medium Medium Three-lane Faster Medium High Medium High Medium Three-lane Shifted Low Medium High High High Legend: Low to Zero Impacts: Green Medium Impacts: Orange High Impacts: Red 5.3.3 Schedule Because of the local weather patterns, the available window for construction is limited. The estimated timeframe in which construction can progress is from the beginning of April to the end of October, with potential bleed into March and November when the weather is favorable. The City indicated a period of downtime, June 15 to July 11, to accommodate events and festivals held in Aspen. With that, it is estimated there is approximately 5 to 6 months each year in which construction activities can occur. Based Only one phasing option applies to the two-lane bridge alternative. For the three-lane bridge alternative, the Three-lane Centered provides the best overall scenario for construction. However, this option also creates the most impact to travelers (vehicular and pedestrian). The Three-lane Shifted is the best scenario for travelers, but it encounters considerable project risks and property impacts. 78 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 59 on the superstructure types considered for the replacement, it is estimated each phase would take between 4 to 6 months to complete. This works out to about one phase of construction completed per calendar year. When considering the impacts of a single traffic lane on the accessibility of SH 82 into or out of Aspen, the duration in which this lane would be in place is important to understand. For the two-lane replace and the three-lane centered option, the single traffic lane would be required for approximately 2 years. As discussed for the two-lane replace option, pedestrian access could be maintained on the bridge throughout the duration of construction, but it would require the single traffic lane for an additional year. Also discussed was the removal of the pedestrians from Phase 2 of the two-lane alternative and for the three-lane centered option. This would allow for one phase to be removed and would reduce the overall duration of construction to 3 years. Table 7 presents a summary of the total construction duration and impacts to SH 82 for the construction phasing options considered. The SH 82 Impact Duration considers the time in which SH 82 would require maintenance of traffic control, slower speeds, or shifted lane locations. Table 7. Summary of Construction Duration and Impacts Phasing Option Total Construction Duration SH 82 Impact Duration Single Traffic Lane Duration Two-lane Replace 4 years 3 years 2 years Three-lane Centered 4 years 3 years 2 years Three-lane Faster 3 years 2 years 1 year Three-lane Shifted 4 years 3 years 0 years NOTE: Assumes a typical calendar year with the following months and partial months for construction: Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 5.4 Cost Estimate Preliminary bridge cost estimates prepared for this feasibility study are high-level estimates and should not be considered final. These estimates are more so to compare the different phasing options and superstructure types. Cost per square foot of bridge were the basis of these cost estimates. This data is available from CDOT; however, as steel and cast-in-place concrete girders are not common in Colorado, cost data from other states such as California, Washington, and Wisconsin were referenced. (CALTRANS 2019; CDOT 2023b; WSDOT 2020; WISDOT, 2023) Additionally, a bridge cost estimate specialist from For all options, construction duration ranges from 3 years to 4 years, with only a portion of each calendar year open to construction. Construction duration for the bridge replacement option is primarily a function of the available detour routes. If all traffic could be routed to an offline location to allow for full bridge closure, the bridge could be replaced quickly when compared to having to keep the bridge open to traffic during the replacement. Construction phasing of the bridge quadruples the time required for replacement. 79 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 60 Jacobs was consulted to determine how the complexities associated with this site and location would factor into the bridge cost estimates. In addition to the cost of the new bridge, ROW acquisitions for approach tie-ins were also included. As discussed in Section 5.3.2, ROW acquisitions were required for the three-lane faster and shifted options. Refer to Section 7 for additional costs for Temporary Construction Easements. Table 8 provides a summary of the costs for the replacement alternatives. The costs of the cast-in-place concrete and steel superstructures are fairly similar, with steel being slightly more expensive. The two-lane replace and the three-lane centered options are also similar, while the three-lane is slightly more expensive because of the additional width. However, it may be more economical to construct the three- lane centered, because the total cost of the bridge during its service life is anticipated to be less than the two-lane replace, given no future widening would be needed to accommodate the third lane. Three-lane Faster and Shifted have additional ROW acquisitions and are significantly more expensive as a result. Table 8. Summary of Alternative Cost Estimates Material Alternative Bridge Cost per Square Foot Bridge Area (Square Foot) Bridge Cost ROW Acquisition (Square Foot) Cast-in- place Concrete Two-lane Replace $450 21,125 $9,500,000 0 Three-lane Centered $450 22,048 $10,000,000 0 Three-lane Faster $450 24,557 $11,100,000 574 Three-lane Shifted $450 22,048 $10,000,000 673 Steel Two-lane Replace $475 21,125 $10,000,000 0 Three-lane Centered $475 22,048 $10,500,000 0 Three-lane Faster $475 24,557 $11,700,000 574 Three-lane Shifted $475 22,048 $10,500,000 673 The costs in Table 8 are not complete project costs because other costs for mobilization, traffic control, site civil work for roadway approaches, and any other non-structural items are not included. Section 7 discusses and calculates the overall project costs associated with each alternative. 5.5 Accelerated Bridge Construction Accelerated bridge construction (ABC) uses innovative planning, design, materials, detours, and construction methods in a safe and cost-effective manner to reduce the onsite construction time that occurs when building new bridges or replacing and rehabilitating existing bridges. ABC improves site constructability, total project delivery time, and work-zone safety for the traveling public. In the most ideal cases, ABC also reduces traffic impacts, onsite construction time, and weather-related time delays, which can be significant in Colorado. This project investigated several ABC techniques and analyzed each to determine which, if any, would be a good fit for this spatially constrained site. Using ABC on projects will typically save construction time while adding construction cost. Each project needs to decide if this trade-off, along with the added cost, is worth it. 80 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 61 5.5.1 Self-propelled Modular Transporter Move First, the project investigated if a self-propelled modular transporter (SPMT) bridge move was an option. This option would build the superstructure offline on temporary supports and then move it into place after the existing bridge is demolished for the new substructure to be built. The SPMT includes hundreds of wheels to move the bridge in place and is controlled by a computer. An example of this type of construction is shown on the images in Figure 47. The superstructure is moved off the temporary supports with the SPMT in the left photo, and the SPMT drives the superstructure into position to rest on the new substructure in the right photo. Figure 47. Self-propelled modular transporter construction on Minnesota Department of Transportation Maryland Avenue Bridge This method requires ample site space nearby to stage and build the new superstructure. The site must be flat terrain to “drive” the superstructure into place and set it on the new substructure, with all the wheels of the SPMT working together. The Castle Creek site does not have enough space to build the new superstructure, and the steep terrain surrounding the bridge is not conducive to an SPMT move. 5.5.2 Incremental Bridge Launch With steep terrain, an incremental bridge launch could be a beneficial ABC option. For a bridge launch, the bridge is typically built on the same alignment as the final bridge layout, then incrementally launched out to slide over each pier as it goes from one abutment to the next. A launch pit is built in the roadway area ahead of the bridge location, where the bridge sections are aligned, connected, and then pushed forward. Figure 48shows an example incremental steel bridge launch using hydraulic jacks. 81 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 62 Figure 48. Incremental Steel Bridge Launch at the Athabasca River Bridge With SH 82 (Hallam Street) being the main route for Aspen, an incrementally launched bridge at this location is less feasible, requiring a full shutdown of the road for months while the bridge is built along the alignment to launch. Within the shutdown for construction, there will also be periods of time when Power Plant Road will require closure for safety critical activities, such as existing bridge demolition and steel launching. Closures on Power Plant Road then cut off the only existing detour to SH 82 during construction. The construction limits are also extended to accommodate the launch pit, excavated in the roadway ahead of the bridge location. The lack of an existing detour and an extended full closure period are major conflicts, negating the benefits of an incremental launch at this site. Because of the major constraints, an incremental launch was not considered further as a viable method. An incremental launch sequence is shown on Figures 43a and 43b in Appendix E, indicating the conflicts for this site. 5.5.3 Slide-in Bridge Construction Another ABC option investigated was the bridge slide, which is built offline similar in nature to the SPMT bridge move. With a bridge slide, the new superstructure is built directly adjacent to the existing bridge on temporary supports. The new substructures (piers and abutments) are built in their permanent location. The bridge is then slid into place, transferring the superstructure from the temporary supports to the permanent substructure. Slide-in bridge construction (SIBC) was used on the State Highway 266 over Holbrook Canal Bridge, as shown on the images in Figure 49. The left photo shows the bridge superstructure sliding into place with a hydraulic jack, while the right photo highlights the temporary supports that were built for the superstructure before sliding into the final position shown in the background. SIBC is most advantageous when used on single span bridges. 82 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 63 Figure 49. Slide-in Bridge Construction at the Colorado Department of Transportation State Highway 266 over Holbrook Canal Bridge While the piers could primarily be built underneath the existing bridge, the abutments must be built with lane closures. Like the SPMT option, a typical bridge slide requires a 6- to 8-day shutdown to complete the operation. However, at this location, a shutdown of SH 82 would be about 1 month because most of the abutment and approach work cannot be performed ahead of the closure. Given the height of the existing bridge, the temporary piers and abutments will be both costly and impractical at the SH 82 site. The following site constraints must be considered for a bridge slide of the CCB: Gas Regulator Station: An existing gas regulator station is adjacent to the southwest corner of the existing bridge. The temporary bridge location would likely interfere with the gas regulator station, which contains high pressure gas for much of the City area. Impacts to this station and the lines from it is highly dangerous, and relocating the station would be both expensive and impactful to the environmental site because it is in an open space area. Temporary Pier Locations: The location of the temporary piers must align with the proposed piers. With Power Plant Road crossing underneath the bridge in two locations (horizontal curve), locating piers to avoid Power Plant Road in both the temporary and permanent construction will be difficult without impeding traffic on Power Plant Road. Utilities: Currently, nine utility conduits run along the existing bridge, carrying utilities for multiple providers. To accommodate a bridge slide, these utilities would need to be either temporarily or permanently relocated to a separate support, similar to small bridge directly north of the existing bridge. Residential Properties: To build offline to the south on the temporary supports, the bridge superstructure would be built overtop of at least one residential property. This is a significant risk for the project, and contractors will avoid this interaction and risk. Power Plant Road Access: Currently, Power Plant Road is the only detour route to SH 82. As soon as the existing bridge demolition starts, Power Plant Road will need to be closed to traffic for safety during demolition. The road will also be closed during the slide. With SH 82 and Power Plant Road concurrently closed for extended periods during the construction, there will be no emergency route available. Given these site constraints, SIBC would present more impacts than benefits. A typical bridge slide is shown on Figure 49a, and major conflicts toward using this method are shown on Figure 49b, both in Appendix F. 83 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 64 5.5.4 Prefabricated Bridge Elements and Systems All precast elements are considered forms of ABC, and this project investigated using precast concrete deck forms, along with precast/prestressed girders. Precast elements allow for the casting of the concrete to be performed offsite instead of having to wait for long curing times at the bridge site. This has a dramatic impact on project schedule and is the construction method of choice in the State of Colorado. Both Colorado Bulb-T’s and Colorado Decked Bulb-T’s were considerations for this project. However, all precast girder options have been eliminated because of their heavy pick weights when compared to other superstructure types. Precast, prestressed concrete girders that accommodate a three- or four-span configuration require two large cranes to pick and place each girder. Both cranes would need to be brought to the site in pieces and transported into place from the top of the existing bridge to the ground below, where it would be assembled. Picking and placing these heavy girders with such large cranes is not impossible, but it is challenging and costly enough for the team to look at alternative options. Because precast/prestressed concrete girders are eliminated, so are their counterparts, precast concrete deck panels. Other ABC options worth considering were prefabricated bridge elements and systems like pre-decked girder systems. These are preassembled girder pairs with a concrete deck placed on top. The system is picked and placed on the newly constructed substructure units and require closure pours between each of the elements. This system was also eliminated for the same reason the concrete girders were; the sheer weight of the girder picks requires very large cranes that cannot fit within the construction footprint area. Table 9. Accelerated Bridge Construction Summary ABC Method Brief Description Fatal Flaw at CCB SPMT Move “Driving” the superstructure into position to set on the new substructure Steep terrain is not conducive to SPMT machine Incremental Bridge Launch “Pushing” the superstructure across from one side to the other side for the bridge length Extended full closure of SH 82 cuts off access to the City SIBC “Sliding” the superstructure over from temporary supports to the new substructure Existing facilities under SH 82 conflict with the temporary bridge location Prefabricated Bridge Elements and Systems Using prefabricated (typically precast concrete) elements to expedite construction Existing facilities under SH 82 prohibit needed space for cranes to erect precast elements While not considered an ABC method by definition, a full closure of the bridge would provide the fastest construction method. This requires a new, viable detour for all traffic for full demolition of the existing bridge before reconstruction on the same alignment. Refer to Sections 5.3 and 6 for additional discussion related to schedule and detours. 84 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 65 6. Traffic Impacts This section summarizes potential traffic impacts caused by the bridge reconstruction or rehabilitation. 6.1 Existing Traffic Conditions CCB supports SH 82, which is functionally classified as a Principal Arterial. SH 82 in this area contains one travel lane in each direction and has a posted speed limit of 25 mph. Understanding traffic impacts for construction activities starts with reviewing existing traffic conditions in the busiest time period(s) of the day, which are the peak hours. This study uses evening peak-hour traffic counts derived from the West End Traffic Study to derive the peak hour volumes traveling outbound or west. This study estimated 600 to 650 vehicles per hour (vph) on Power Plant Road and 1,000 to 1,250 vph on SH 82 (Fox Tuttle 2022). No recent studies have estimates of inbound traffic volumes in the morning peak hour, but inbound traffic backups and congestion commonly occur on SH 82 between 7:00 to 9:00 a.m. during the weekdays. These backups often extend past the Aspen Airport. Commuters into Aspen now try to avoid the backup on SH 82 by detouring over McClain Flats Road. In addition, CDOT’s traffic counter data from 2018 and 2019 indicate no substantial difference in directional vehicle volume inbound and outbound between the hours of 10:00 a.m. and 3:00 p.m. The counter is west of Cemetery Lane. Figure 50. Weekday Traffic Counts on SH 82 between Maroon Creek Road and Cemetery Lane Source: CDOT 2024 While CDOT’s counter and the West End Traffic Study counts were not in the same location, comparison of the data indicates CDOT’s 2018 to 2019 peak hour volume data and the West End Traffic Study SH 82 peak hour volume data are similar in showing the S-curves, the Maroon Creek roundabout, and other In summary, the CCB replacement is a viable candidate for ABC when only considering impacts to the traveling public. However, the proximity of the residents nearby, tight curves of the roadway below, and narrow footprint of the existing bridge make most ABC options untenable. Traditional bridge construction phasing or a full closure of SH 82 are the only options remaining to consider. 85 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 66 traffic constrictions reduce capacity on SH 82 in this area to between 1,000 to 1,400 vph. From the West End Traffic Study, it appears Power Plant Road acts as a reliever route serving outbound traffic bypassing SH 82 by approximately 600 to 650 vph in the evening peak hour. Transit service is another key piece for getting workers and visitors into the town. Currently, 814 buses cross Castle Creek on weekdays, and 841 buses cross on weekends. The Roaring Fork Transportation Authority anticipates the weekday number will rise to 841 crossings in 2025. It will be critical in any rehabilitation or reconstruction scenario that transit be prioritized as much as possible. Three Aspen School District routes cross CCB twice per day for elementary students and again for the older kids. Aspen Country Day School also has at least one route crossing twice per day. In total, there are at least 14 school bus crossings. 6.2 Maintenance of Traffic Options Bridge construction would require lane closures and greatly disrupt traffic movement along the already- congested SH 82. The following subsections discuss various detour and bridge options to manage traffic and prioritize bus services during construction or rehabilitation of CCB. A summary of the traffic impacts for the alternatives is as follows: 1. Bridge Rehabilitation and Two-lane Bridge Construction a. Alternating single lane b. Inbound CCB lane with outbound detour—West End Detour (Power Plant Road) c. Outbound CCB lane with inbound detour—Temporary Detour across Marolt-Thomas 2. Three-lane Bridge Construction a. Centered: One-lane bridge during all construction phases with companion detour b. Faster: One-lane bridge during Phase 1 construction with companion detour; two-lane traffic across bridge during other construction phases c. Shifted: Two traffic lanes across bridge during all construction phases 86 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 67 Figure 51. Outbound and Inbound Detour Options during Castle Creek Bridge Reconstruction or Rehabilitation Table 10 summarizes the detour scenarios and their performance. Table 10. Summary of Maintenance of Traffic Options and Performance Legend: Low to Zero Impacts: Green Medium Impacts: Orange High Impacts: Red *Alternating Single Lane and West End Detour deemed not feasible due to extended traffic delays & gridlock **Maximum Estimated Delay in Queue. Actual travel delays would require a traffic model. Maintenance of Traffic Scenario Handles Outbound Peak Period Handles Inbound Peak Period Handles Emergency Egress Periodic Closures of Detour Pedestrians and Bicycle Impacts Environmental Impacts Maintenance of Traffic Cost Transit/School Bus Delays General Vehicle Travel Delays** Existing Conditions (Baseline) ✓ ✓ ✓ N/A Low N/A N/A Low ½ hr Alternating Single Lane* Med Low Med High 7 hrs Inbound CCB Lane with Outbound Detour – West End Detour (Power Plant Road)* ✓ ✓ High Low Med Med 5 hrs Outbound CCB Lane and Inbound Detour – Temporary Detour Marolt-Thomas ✓ ✓ ✓ Low Med High Low ½ hr Phased Two Way Traffic Across CCB ✓ ✓ ✓ Low Low Low Low ½ hr 87 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 68 6.3 Bridge Rehabilitation and Two-lane Bridge Construction Options to accommodate traffic during a two-lane bridge rehabilitation or two-lane bridge construction are detailed in the following subsections. 6.3.1 Alternating Single Lane A common approach to managing traffic during bridge construction is operating and signalizing an alternating single lane. This operation is applicable for maintaining one lane of traffic across the bridge for either rehabilitation or reconstruction work. The Highway Capacity Manual (TRB 2010) indicates a single lane work zone can pass 1,400 vph. Under a single lane two-way operation, that capacity would be split between each direction of travel. Assuming 15% of bridge capacity is lost to the safe clearance bridge traffic, each direction of travel is estimated to have a capacity of roughly 600 vph under an alternating (inbound/outbound) single lane operation. As shown on Figure 51, inbound traffic counts exceed 600 vph between 7:00 a.m. and 7:00 p.m., while outbound traffic counts exceed 600 vph between 8:00 a.m. and 8:00 p.m. Therefore, without efforts to mitigate or reduce travel demand, any alternating single lane configuration would generate a continuously increasing backup condition on either side of construction. Weekday queues in the inbound direction would begin at 7:00 a.m. and last into the evening, with several thousand vehicles in a queue extending beyond the town of Basalt. Weekday queues in the outbound direction would begin around 8:00 a.m. and last into the evening. Several thousand vehicles would queue on SH 82 in Aspen and on surrounding Aspen streets, causing a gridlock condition in west Aspen and SH 82. Refer to Figure 52 for a visualization of the inbound queue length. 88 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 69 Figure 52. Inbound Queue Length with Alternating Single Lanes Across the Bridge For this scenario, temporary signals would be placed at each end of the bridge to facilitate the alternating single lane operations. Where space permits, buses could be moved to the front of the signal queue, both transit and school bus service would be impacted and delayed up to 1 hour each day. Pedestrian traffic across the bridge would be maintained or accommodated, depending on whether rehabilitation or the two-lane bridge replacement is chosen. Emergency service response times in an alternating single lane configuration would be severely impacted and delayed by the construction traffic, but the usual protocol of moving to the side to allow emergency vehicles to pass would still be applicable and allow access to the hospital, albeit with slower response times. To plan for a wildfire or other emergency evacuation, a construction protocol would be developed to require inbound traffic to be stopped and outbound traffic to have right of way on the single lane on the bridge for as long as it took to clear town. Current estimates from the City indicate the time needed to evacuate the town would take over 11 hours. This time estimate factors reversing both existing lanes across the bridge and through the roundabout to facilitate outbound flow. All bridge rehabilitation and 89 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 70 single lane construction options would limit outbound capacity to a single lane across the bridge, reducing the outbound flow and increasing the amount of time to evacuate. The alternating single lane configuration is not a viable option for maintaining normal traffic flow, transit priority, or providing emergency egress. Removing the alternating signals would still allow traffic to navigate the bridge in one direction but would need a companion detour in the other direction. The following subsections describe potential one-lane detour used in conjunction with a single lane across phased bridge work (Figure 51). 6.3.2 Inbound Castle Creek Bridge Lane with Outbound Detour—West End Detour (Power Plant Road) One lane of (outbound) traffic could detour down north 7th Street to West Smuggler Road and Power Plant Road (currently limited by restrictions on oversize vehicles) while the inbound lane uses one lane over the bridge during phased construction. Along Power Plant Road, turning radii, pavement widths, curve widening, vertical grades, and the small bridge over Castle Creek would be evaluated to determine whether a one-way (outbound) condition would allow the use of oversize vehicles on the route. As noted previously in this section, the current evening peak hour traffic volume on this route is approximately 600 to 650 vph; however, roadway improvements and an added signal on Cemetery Lane would enhance the capacity of this detour to between 800 and 1000 vph. However, Jacobs estimates there would still be a substantial backup into the west end neighborhoods because the total demand can’t be served. Maximum delays to travelers are estimated to be up to 5 hours, in the evening peak hour for each day of construction. Mitigation options are available, such as a temporary signal at the intersection of Cemetery Lane and Power Plant Road, and modifications to the signal cycle at SH 82 and Cemetery Lane to help clear traffic faster. Other travel demand mitigation options, such as increased bus service to the Brush Creek Intercept Lot, would also be explored. Depending on the detour scope and needs, improvement costs to Power Plant Road is estimated to be $3 to $5 million. And during construction or rehabilitation of CCB, Power Plant Road, which winds underneath the bridge, may be closed periodically, limiting its use as a reliable detour. Closures could be related to falsework placement or adjustments under the bridge or the movement of equipment and materials into staging areas below the bridge. Falsework is needed for the preferred cast-in-place concrete construction technique. If a steel solution was picked, then cranes would be occupying portions of Power Plant Road. Under this scenario, travelers trying to access the hospital and high school and those trying to evacuate for emergencies would experience similar delays as those described in the alternating single lane configuration. Pedestrian traffic would be accommodated across the bridge or along Power Plant Road, depending on which construction alternative is selected. Transit and school bus priority could be managed by keeping these essential services on the current SH 82 route and using flaggers at each end of the bridge to send them across the bridge with delays kept to less than 30 minutes. This would be similar to how the city manages transit priority when outbound traffic is shifted to Power Plant Road during CCB maintenance or repairs. Because of the long queues, gridlock, and egress risks, the alternating single lane option is untenable for SH 82 travelers and destinations served by these users, including local businesses. 90 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 71 To plan for a wildfire or other emergency evacuation, a construction protocol would be developed to require inbound traffic to be stopped and outbound traffic to have right of way on the single lane on the bridge for as long as it took to clear town. Current estimates from the City indicate the time needed to evacuate the town would take over 11 hours. This time estimate factors reversing both existing lanes across the bridge and through the roundabout to facilitate outbound flow. All rehabilitation or reconstruction options that offer a single lane on CCB would limit outbound evacuations to a single lane across the bridge causing a choke point that would increase evacuation time, thereby creating a large risk for the City and its citizens. 6.3.3 Outbound Castle Creek Bridge Lane with Inbound Detour—Temporary Detour across Marolt-Thomas A temporary one lane detour route could be constructed to split one lane of eastbound (inbound) traffic from SH 82 to the south, using an existing transportation easement across the Marolt-Thomas open space, and then spanning Castle Creek with a temporary bridge to join SH 82 on West Main Street into Aspen. This detour route, while similar in alignment to the preferred alternative, could be constructed across the existing easement to meet the peak morning incoming volumes of nearly 1,100 vph while maintaining a single lane on the existing bridge serving westbound (outbound) traffic. Depending on detour scope and needs, construction costs for this inbound detour are estimated at $13 million. Unlike the outbound detour with its periodic closures, the inbound route would remain open during construction or rehabilitation of CCB. This option temporarily impacts open space; however, the detour could be removed at the end of the CCB construction and the open space restored to its natural state. In this scenario, access to the hospital and the high school would be similar to the existing condition. However, the inbound detour lane could be reversed and serve as outbound emergency evacuation egress in conjunction with CCB. This detour option provides the town an additional evacuation route during construction, and if desired, the temporary bridge could also be left in place for facilitating future evacuation efforts. With an inbound detour pedestrian and bicycle traffic could be accommodated across Castle Creek via the temporary bridge and follow along the detour to make their trail connections. This would be a safer path for pedestrians since they would not need to cross a bridge under construction or rehabilitation. Transit and school bus priority would be no different than current SH 82 conditions with minimal delays expected in normal peak period congestion. Using a West End Detour (Power Plant Road) will not be a reliable, cost-effective detour considering travelers would experience up to 5-hour outbound delays and periodic detour closures. During construction of the CCB, the inbound detour across the Marolt-Thomas open space is the most reliable detour for minimizing travel delays, prioritizing transit service, and providing safe pedestrian access and reliable evacuation routing. If the City determined it was a high priority to minimize the bridge project’s duration and impacts to the community, this detour route could be evaluated for carrying two lanes of traffic (inbound and outbound). 91 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 72 6.4 Three-lane Bridge Construction Options to accommodate traffic during a three-lane bridge construction are detailed in the following subsections. 6.4.1 Centered—One-lane Bridge During All Construction Phases with Companion Detour For this option, the bridge is optimally placed to minimize construction impacts. The alternating single lane configuration and the West End Detour option are not a viable for maintaining normal traffic flow or providing emergency egress. Therefore, for this construction option, a single lane of outbound traffic across the bridge is maintained in conjunction with an inbound detour, as described in Section 6.3.3. All traffic impacts and mitigations identified in Section 6.3.3 apply in this scenario. Pedestrian access could still be maintained across the bridge with minimal interruptions or diverted over the inbound detour with no interruptions and a safer path. In this scenario, access to the hospital, high school, and emergency evacuation egress would be similarly delayed or mitigated according to Section 6.3.3. 6.4.2 Faster—One-lane Bridge During Phase 1 with Companion Detour; Two-lane Traffic During Subsequent Phases For this option, the bridge is shifted to the south, allowing for sufficient width to provide continuous two lanes (inbound and outbound) during construction. However, in Phase 1, a single lane of outbound traffic across the bridge is required in conjunction with an inbound detour, described in Section 6.3.3. All impacts and mitigations defined in Section 6.3.3 apply in Phase 1 only. In all other phases, this option would function similarly to two-way existing conditions. Refer to Section 6.4.3 for additional traffic information. Pedestrians and bicyclists would be routed under the bridge in all phases subsequent to Phase 1 to allow the width for two temporary lanes. Pedestrian access would be impacted when bridge construction impacts the pedestrian path below the bridge. However, with a separate inbound detour, safer and uninterrupted pedestrian access could be facilitated by rerouting pedestrians and bicyclists over to the inbound detour. In Phase 1, access to the hospital, high school, and emergency evacuation egress would be similar to Section 6.3.3 with minimal delay. All other phases would be similar to existing conditions where both lanes would be converted to facilitate outbound flow during an evacuation event. Transit and school bus priority would be no different than current SH 82 conditions with minimal delays expected in normal peak period congestion. 6.4.3 Shifted—Two-lane Bridge During All Phases To facilitate this option, a shift of the replacement bridge is required. Jacobs estimates maintaining two lanes of traffic through the construction for a bridge replacement would have a minimal impact on the current traffic condition. The Highway Capacity Manual (TRB 2010) indicates a single lane work zone can pass 1,400 vph. The capacity of the temporary lanes on the bridge is comparable or greater than the prevailing S-Curve capacity limitations. Construction conditions may constrain flow through the S-Curves for short durations (up to 15 minutes) but is not expected to increase daily queues and delays noticeably more than existing conditions. 92 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 73 Pedestrians can use the northern sidewalk until the final phase (the construction of the north side of the bridge). During this final phase, pedestrians will be rerouted to Power Plant Road. It is possible to keep the pedestrians on the bridge during construction of all phases; however, it requires an even wider overbuild. In this option, access to the hospital, the high school, and emergency evacuation egress would operate similarly to existing conditions. Both lanes would be converted to facilitate outbound flow during an evacuation event. 7. Overall Project Costs This section summarizes potential overall project costs associated with bridge reconstruction or rehabilitation and factoring other ancillary costs. A matrix of overall project costs for the different bridge rehabilitation and reconstruction are found in Appendix K. 7.1 Other Project Costs The bridge costs detailed in previous sections have noted additional project costs. This section elaborates on those costs. 7.1.1 Unlisted Construction Items Unlisted items include high-cost items associated with construction costs. • Mobilization – cost associated with mobilization of construction equipment, estimated at 15% of bridge construction cost. • Removal of Existing Castle Creek Bridge –cost to safely demolish and remove the existing bridge while the new bridge is constructed. • Utilities – cost associated with relocation of City-owned utilities. Relocation of private utilities will be at the expense of the utility owner. • Roadway Approaches – cost of all roadway improvements needed to tie the new bridge to the existing roadway. • Temporary Detour Construction – cost associated with construction of the detour route. For the inbound detour, the cost assumes constructing an 11-foot lane detour road with 4-foot shoulders, a 10-foot paved trail that parallels the detour road, and a temporary bridge over castle creek. • Traffic Control and Transit/School Bus Priority – cost of daily maintenance of traffic operations and temporary traffic control devices (traffic signs, cones or barrels and variable message signs) or staff such as flaggers utilized during construction. • Other Contingencies – a contingency factor of 20% was applied to account for all other unlisted construction items that may be smaller in nature. 7.1.2 Planning (NEPA) and Design Engineering design costs are estimated as 15 percent of the construction replacement cost and 10 percent for a rehabilitation project. This would include developing preliminary and final plan drawings, specifications and final construction estimate for the City to bid the project. 93 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 74 NEPA costs for the bridge reconstruction options assume that a new Environmental Impact Statement (EIS) and Record of Decision (ROD) will be required. The estimated cost for the two-lane bridge scenario is $2M, the three-lane bridge is estimated at $3M. 7.1.3 Right-of-Way and Easements Right-of-way acquisitions are anticipated for certain bridge alternatives as noted in Section 5.4. The cost associated with ROW was assumed to be $8,000 per square foot as directed by the City based on recent projects. Construction easements may also be required for construction activities or staging of materials outside of the right-of-way. For estimating purposes, it is assumed that the bridge rehabilitation and two-lane replace will require a 10-foot wide easement along the south side of the bridge across two properties (~300-feet). The bridge reconstruction assumes a range between 10 and 20-foot wide easements through the same two properties on the south side of the bridge at similar lengths. Temporary easement costs are estimated at $1,500/square foot. Table 11. Estimated Right-of-Way and Easement Costs Material Alternative Easement Costs ROW Cost N/A Rehabilitation $4,500,000 $0 Cast-in-place Concrete Two-lane Replace $4,500,000 $0 Three-lane Centered $4,500,000 $0 Three-lane Faster $10,500,000 $4,600,000 Three-lane Shifted* $15,750,000 $5,400,000 Steel Two-lane Replace $4,500,000 $0 Three-lane Centered $4,500,000 $0 Three-lane Faster $10,500,000 $4,600,000 Three-lane Shifted* $15,750,000 $5,400,000 *Additional ROW and Easement costs could be needed along SH 82 (Hallam St) depending on final roadway alignment shift. 7.1.4 Public Involvement Public involvement costs are those associated with public communication and stakeholder engagement during construction, such as informing people about lane closures, business access impacts, work hours and work zones, and detours. Public communication methods can include project information meetings/open houses, mass mailing of project information flyer/brochures, and project website/social media sites. Public involvement is estimated as $1,200/day for construction duration. 7.1.5 Construction Engineering and Indirects (CE&I) Construction engineering costs include the supervision, inspection and quality control of materials during construction activities. Indirect costs are costs that are incurred for the benefit of the project (City staff and CDOT time) that are not project specific. The CE&I cost has been estimated as 26 percent of the construction cost. CDOT construction projects also factor the same 26 percent. 94 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 75 7.2 Overall Project Costs The 2024 total project costs are a summation of the bridge costs and other project costs listed in Section 7.1. A year over year inflation rate of 4% was applied to project costs for calendar year 2028. Table 12. Summary of Overall Costs for Options Project Year Rehabilitation Two-Lane Replace (CIP) Three-Lane Centered (CIP) Three-Lane Faster (CIP) Three-Lane Shifted (CIP) Overall Project (2024) $43.61M $68.58M $72.95M $81.85M $69.28M Overall Project (2028) $51.01M $80.23M $85.34M $95.75M $81.05M Three-lane Shifted costs come in favorable to the Two-Lane Replace and Three-Lane Centered because the shifted option does not require a detour. 7.3 Economic and User Costs Construction related delays would result in severe congestion or traffic halts that will increase user costs for residents and visitors. Travelers might be required to wait in lengthy queues or use detours to reach their destinations or might opt to postpone or cancel their trip. The construction related delay would add additional VMT and VHT during the construction period. While construction of the project would only occur over designated months, the roadway impacts are expected to be year-round. Depending on the alternative selected, construction is expected to last between two and eight construction seasons and the delay impacts are expected to last one to four years. Delay costs can be estimated using input values provided by the U.S. Department of Transportation’s (USDOT’s) Benefit-Cost Analysis Guidance for Discretionary Grant Programs (USDOT 2024). The assumptions and inputs used in the user costs calculations used standard inputs and values from USDOT’s BCA guidance such as vehicle occupancy rates, value of time, and vehicle operating costs. Mode split between personal vehicles and commercial vehicles and the estimated travel delay in the network was estimated by Jacobs traffic engineers. Construction related travel delays are expected with the Alternating Single Lane scenario and the West End Power Plant Road detour scenario. Applying the appropriate traffic inputs and USDOT values we estimated both of these scenarios would exceed $100 Million in annual user costs. Granted some folks when stuck in construction traffic would begin to make behavior changes and switch to mass transit or stay home, but that level of change may only amount to 30 percent savings on user costs. In Subsection 6.3.1 and 6.3.2 we ruled out these options as untenable due to travel delay and the associated annual user costs (> $100M) reinforce that decision. Both the Inbound temporary detour across the Marolt-Thomas (with outbound lane across the CCB) and the phased two-lane bridge construction (Three Lane Shifted) is estimated to function most closely to existing conditions and have negligible user costs when compared to a West End Power Plant Road detour and an Alternating Single Lane scenario. 95 SH 82 Over Castle Creek Bridge Feasibility Study 240207140925_5d9775bf 76 8. References American Association of State Highway and Transportation Officials (AASHTO). 2016. Manual for Assessing Safety Hardware. Washington, D.C. American Association of State Highway and Transportation Officials (AASHTO). 2020. LRFD Bridge Design Specifications. 9th edition. May. California Department of Transportation (CALTRANS). 2019. Comparative Bridge Costs. January. City of Aspen. 2017. Project No. 2014-019, Hallam Street – Castle Creek Bridge. December. City of Aspen. n.d. Topographic Survey Drawing. Provided to Jacobs in September 2023. Colorado Department of Highways (CDOH). 1954. Federal Aid Project No. S 0130 (4), Colorado Highway 82 Bridge Over Castle Creek Near Aspen. January. Colorado Department of Transportation (CDOT). 1998. Technical Memorandum. December 7. Colorado Department of Transportation (CDOT). 2009. CDOT Structure Inspection and Inventory Report. Colorado Department of Transportation (CDOT). 2022. CDOT Structure Inspection and Inventory Report. Colorado Department of Transportation (CDOT). 2023a. Bridge Design Manual. February. Colorado Department of Transportation (CDOT). 2023b. 2022 Cost Data. March. Colorado Department of Transportation (CDOT). 2024. Traffic Data Explorer. https://dtdapps.coloradodot.info/otis/trafficdata. Fox Tuttle. 2022. West End Neighborhood Traffic Study. June. Engineering Operations(eO). 2023. In-depth Superstructure Investigation Report. National Bridge Inventory (NBI) Database. Federal Highway Administration. February 9. https://www.fhwa.dot.gov/bridge/nbi/ascii.cfm. Regional Transportation District (RTD). 2018. Light Rail Facility Design Guidelines and Criteria. Denver, Colorado. April. Schmueser Gordon Meyer (SGM). 2008. Feasibility Study Update: State Highway 82 – Maroon Creek Roundabout to Main Street Reversible Lane. May. Transportation Research Board (TRB). 2010. Highway Capacity Manual, 6th Edition: A Guide for Multimodal Mobility Analysis. Washington, D.C.: National Academies of Science, Engineering, and Medicine. Washington Department of Transportation (WSDOT). 2020. Bridge Design Manual (LRFD). September. Wisconsin Department of Transportation (WISDOT). 2023. Bridge Manual. July. 96 Appendix A 2022 Structure Inspection and Inventory Report by CDOT 97 98 99 100 101 102 103 Structure No. H-09-B Inspection Date: 9/7/2022 Team: Gold CDOT Bridge Inspections Page 1 of 3 Active Construction at Abutment 1 on Joint Construction Debris at Abutment 1 104 Structure No. H-09-B Inspection Date: 9/7/2022 Team: Gold CDOT Bridge Inspections Page 2 of 3 R3 - R4 Corrosion of Girder 5F near Abutment 6 Bearing Loss Due to Missing Grout Pad Under Bearing 6B 105 Structure No. H-09-B Inspection Date: 9/7/2022 Team: Gold CDOT Bridge Inspections Page 3 of 3 Broken Bearing Pad under Bearing F at Abutment 6 15 Percent Bearing Loss Bearing 6F isTilting to the Rear 106 Appendix B H-09-B (Castle Creek Bridge), In-depth Superstructure Investigation Report by Engineering Operations, LLC (eO) 107 H-09-B (CASTLE CREEK BRIDGE) IN-DEPTH SUPERSTRUCTURE INVESTIGATION REPORT Prepared for: JACOBS ENGINEERING, CITY OF ASPEN Prepared by: Engineering Operations, LLC November 28th-30th, 2023 108 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen 1 TABLE OF CONTENTS TABLE OF CONTENTS...............................................................................1 LIST OF FIGURES.......................................................................................2 BRIDGE INFORMATION .............................................................................3 INSPECTION TEAM ....................................................................................4 1.0 EXECUTIVE SUMMARY.....................................................................5 2.0 PROCEDURE/SCOPE.........................................................................7 3.0 SUMMARY OF FINDINGS ..................................................................8 3.1 Interior Girder Finding Details.........................................................9 3.2 Exterior Girder Finding Details .....................................................10 3.3 Girder Bearing Finding Details .....................................................11 3.4 Diaphragms..................................................................................11 4.0 MAINTENANCE RECOMMENDATIONS..........................................12 5.0 CONCLUSION...................................................................................12 6.0 APPENDICES.............................................................................A6.1.1 6.1 PHOTO LOG..........................................................................A6.1.1 6.2 DEFECT DRAWINGS............................................................A6.2.1 6.3 TALLY SHEET.......................................................................A6.3.1 109 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen 2 LIST OF FIGURES Figure 1: South Elevation...............................................................................................................................................................A6.1.2 Figure 2: General Superstructure of Spans 1 & 2..........................................................................................................................A6.1.2 Figure 3: General Superstructure of Spans 3, 4, & 5.....................................................................................................................A6.1.3 Figure 4: Span 1 Underdeck, Looking West...................................................................................................................................A6.1.3 Figure 5: Span 2 Underdeck, Looking West...................................................................................................................................A6.1.4 Figure 6: Span 3 Underdeck, Looking West...................................................................................................................................A6.1.4 Figure 7: Span 4 Underdeck, Looking West...................................................................................................................................A6.1.5 Figure 8: Span 5 Underdeck, Looking East....................................................................................................................................A6.1.5 Figure 9 :Typical Stiffener Tack Weld Configuration with Crack Code Call-Outs...........................................................................A6.1.6 Figure 10: NSA Cracked Tack Weld – Girder B South Face – Stiffener 19 to Horizontal Leg of Top Flange Angle......................A6.1.6 Figure 11: SA Cracked Tack Weld – Girder B South Face – Stiffener 17 to Horizontal Leg of Top Flange Angle........................A6.1.7 Figure 12: NSA Cracked Tack Weld – Girder C North Face – Stiffener 105 to Vertical Leg of Top Flange Angle........................A6.1.7 Figure 13: NSA Cracked Tack Weld – Girder D North Face – Stiffener 97 to Vertical Leg of Top Flange Angle..........................A6.1.8 Figure 14: NSA Cracked Tack Weld – Girder E North Face – Stiffener 107 to Vertical Leg of Top Flange Angle ........................A6.1.8 Figure 15: SA Cracked Tack Weld – Girder C South Face – Stiffener 16 to Vertical Leg of Top Flange Angle............................A6.1.9 Figure 16: SA Cracked Tack Welds – Girder B South Face – Stiffener 41 to Vertical Leg of TF Angle and Web.........................A6.1.9 Figure 17: NSA Cracked Tack Weld – Girder E South Face – Stiffener 55 to Web.....................................................................A6.1.10 Figure 18: NSA Cracked Tack Weld – Girder C North Face – Stiffener 109 to Web...................................................................A6.1.10 Figure 19: SA Cracked Tack Welds – Girder C North Face – Stiffener 26 to Vertical Leg of Bottom Flange and Web...............A6.1.11 Figure 20: Partially Ground Out Tack Weld – Girder C South Face – Girder Top Flange to Web At Stiffener 16.......................A6.1.11 Figure 21: Fractured Stiffener 16 Weld – Girder C North Face at Bottom - Left..........................................................................A6.1.12 Figure 22: Fractured Stiffener 16 Weld – Girder C North Face at Bottom – Right.......................................................................A6.1.12 Figure 23: Sheared Rivet Head – Girder C North Face at Stiffener 16 Near Bottom...................................................................A6.1.13 Figure 24: Typical Surface Corrosion of Interior Girder at Pier – Girder E South Face at Pier 4.................................................A6.1.13 Figure 25: Surface Corrosion and Minor Pitting in Bottom of Bottom Flange of Girder E at Pier 4..............................................A6.1.14 Figure 26: Laminar Corrosion of Girder E End at Abutment 6 .....................................................................................................A6.1.14 Figure 27: Typ. Pack Rust between Bearing Stiffeners of Int. Girders at Pier – Girder E S. Face at P4 – Stiffener 69...............A6.1.15 Figure 28: Typ. Pack Rust between Bearing Stiffeners of Int. Girders at Abut. – Girder B N. Face at A1 – Stiffener 1...............A6.1.15 Figure 29: Deflection of Stiffener 62 at North Face of Girder B....................................................................................................A6.1.16 Figure 30: Laminar Corrosion in Web and Top of Bottom Flange of North Exterior Girder A......................................................A6.1.16 Figure 31: Laminar Corrosion in Top of Web of North Exterior Girder A......................................................................................A6.1.17 Figure 32: Laminar Corrosion in Web of South Exterior Girder F ................................................................................................A6.1.17 Figure 33: Corrosion Hole in Base of Bearing Stiffener – Girder F at Abutment 6.......................................................................A6.1.18 Figure 34: Load Sag of North Exterior Girder A...........................................................................................................................A6.1.18 Figure 35: Typical Surface Corrosion of Bearing at Pier – Girder B at Pier 2..............................................................................A6.1.19 Figure 36: Typical Anchor Bolt Nut Backed Out and Missing Lock Nut – Girder B at Pier 3........................................................A6.1.19 Figure 37: Impending Spall of Bearing Pedestal of Girder A at Abutment 6................................................................................A6.1.20 Figure 38: Tilted Bearing of Girder F at Abutment 6 ....................................................................................................................A6.1.20 110 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen 3 BRIDGE INFORMATION Table 1: Bridge Information Structure ID H-0-9-B Structure Alias Castle Creek Bridge Place code (Item 4)03620 - Aspen Feature Intersected (Item 6)Castle Creek, Power Plant Rd Facility Carried (Item 7)SH 82 Detour Length (Item 19)1 mi. Year Built (Item 27)1961 Lanes On (Item 28A)2 ADT/Year (Item 30/31)25,000/2020 Posting Status (Item 41)A (not posted) Main Spans Unit (Item 45)5 Structure Length (Item 49)423.6 ft. Width Curb to Curb (Item 51)27.00 ft. Width Out to Out (Item 52)40.00 ft. Superstructure Rating (Item 59)5 Structure Type (Item 120A)RGC (Riveted Girder Continuous) 111 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen 4 INSPECTION TEAM Table 2: Inspection Team Role Personnel Signature Team Leader Nate Proffitt Assistant Inspector Jonathan Ivey QC Reviewer Remy Stern, PE 112 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen 5 1.0 EXECUTIVE SUMMARY The intent of this inspection was to collect comprehensive data on the current condition of the superstructure elements of the Castle Creek Bridge (H-09- B) – predominantly pertaining to the (6) girders that run the full length of the structure. This report details the location, severity, and quantities of a multitude of defects found throughout the superstructure elements. Inspection of the deck and the substructure was not included as part of the scope of this investigation and has not been documented within this report. For details on the condition of the deck and substructure elements, see the most recent routine inspection report data as shown in the Structure Inventory & Assessment (SIA), from the CDOT inspection dated 09/07/2022. Castle Creek Bridge is a 5-span steel multi-girder structure originally built in 1961. The girders are riveted, built-up sections with vertical stiffeners spaced every 3 foot 9 inches on both sides of the girders. The girders are continuous over the piers and thus carry negative and positive moments. In order to gain close proximity and hands on access throughout the lengths of the girders, inspectors utilized an Aspen Aerial UB60 UBIT truck. Inspection was primarily visual, with NDT equipment used as deemed necessary from visual inspection. Special attention was given to areas where vertical stiffeners were tack welded to either the girder web (steel plate 3/8” x 54”) or girder top/bottom flanges (double angles 6” x 4” x 5/8”). Many tack welds are still present on the structure from original construction fit-up and are in-tact. However, many have been found to be cracked and self-arrested (SA) – this condition refers to a completely cracked through tack weld where stress has been relieved and there is no longer potential for crack propagation into the base metal. The remaining tack welds that were cracked but not self-arrested (NSA) were found to be confined to the welds and not propagating into the base metal of the girders. Although there were no locations where cracking was found to enter the girder base metal at NSA tack welds, since the areas are not self- arrested there is a possibility that the crack could make its way into the base metal in the future as it grows. Although it is more likely the crack would make its way through the tack weld and become a self-arrested location, there is always the potential for the crack to migrate into the girder itself. 113 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen 6 Surface corrosion was present in the interior girders (Girders B-E) primarily in 10-15 foot long segments under the deck joints (at piers) and also at the girder ends. No section loss was observed in the interior girders. The exterior sidewalk girders (Girders A & F) had more significant corrosion and section loss. Laminar corrosion was widespread in the lower 6 inches of the web and in the top of the bottom flange resulting in significant section loss to the member in these areas. Some isolated areas of less severe laminar corrosion were found in the tops of the exterior girder webs, typically within 6 inches of the top flange. The superstructure is in overall fair condition. Prior to the inspection, the NBI rating for Item 59 (Superstructure) was a “5”. Per the in-depth investigation, it was found that this rating is accurate and appropriate for the superstructure in its current state. It is recommended to program a cleaning and painting of the exterior girders in order to prevent against further corrosion and maintain current section thicknesses found in the girders. It is also recommended to clean and paint the interior girders within close proximity to the joints in order to arrest current corrosion and prevent future section loss that may occur. Finally, it is recommended to attempt to grind out tack welds that have been identified as “NSA” in order to prevent cracks from forming in the base metal of girders. A more comprehensive (and costly) solution would be to eliminate all tack welds on the structure. 114 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen 7 2.0 PROCEDURE/SCOPE A team of (2) inspectors were on site for a detailed inspection of the superstructure elements between November 28th, 2023 and November 30th, 2023. An Under Bridge Inspection Truck (UBIT) was used to visually inspect all steel girders hands on. The UBIT bucket was deployed from the south lane of the structure to avoid interference within the sidewalk at the north. Traffic control was utilized to fully close the south lane of the structure during inspection times. Fatigue prone details, cracking, areas of corrosion/section loss were closely inspected and documented. The structure and associated stiffeners have been inventoried from West to East; with substructure numbering as follows: Abutment 1, Pier 2, Pier 3, Pier 4, Pier 5, and Abutment 6. Each girder line included 113 stiffeners on each face of the girder – these have been numbered from west to east in accordance with the bridge inventory direction. Girders have been labeled A-F from left to right when looking in the direction of inventory. 115 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen 8 3.0 SUMMARY OF FINDINGS There are numerous tack welds at each stiffener location throughout the lengths of the interior girders. Tack welds were made during construction to fit-up stiffeners to the girders while rivets were being installed. Typically, there are (8) tack welds per stiffener; (2) at the top flange, (4) at the web, and (2) at the bottom flange. In about half of the stiffeners, there is an additional tack weld at the top of the stiffener to the horizontal leg of the top flange angle, and very rarely another tack weld between the vertical leg of the top flange angle and the girder web. See the image to the right for an illustration of tack weld locations, accompanied by a code legend below. See also Figure 9 for an annotated photograph showing a typical stiffener and associated tack welds. The codes that have been used in the legend and graphic shown here have been used throughout the report and drawings in order to more quickly identify the location of a tack weld within the cross section of the girder. These tack welds are of poor quality as they were only intended to be used for ease of construction and are prone to cracking. At the time of original construction, it was typical for contractors to leave tack welds like the ones found on the Castle Creek Bridge in place after project completion. However, in more recent construction, standards have become more stringent and typically require tack welds used for fit-up to be ground out or incorporated into a full structural weld prior to acceptance. Although many locations where tack welds were made have cracked through (self-arrested and considered benign), the concern is focused on welds that have cracked but have not self-arrested (NSA). At these locations, cracks 116 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen 9 cannot definitively be seen to make their way through the entire tack weld and are assumed to still be growing. If too much fusion was obtained during tack-welding between the filler metal and the base metal the potential is increased for these cracks to propagate into girder cross section elements. As seen throughout the structure at self-arrested locations, this scenario was not found to be present – but nonetheless is still possible. 3.1 Interior Girder Finding Details There are (452) stiffener locations throughout the four interior girders, each with (8-9) tack welds, totaling an estimated (3850) tack welds. The majority of the tack welds are still in place and have not cracked. Approximately (415) of the tack welds are cracked but have self-arrested (SA) or have been ground out during efforts in 2011 and are considered to be a benign condition. Approximately (36) tack welds were found to be cracked and not self-arrested. It is imperative to monitor these cracks for propagation during routine inspections if they are not repaired. All tack weld cracks that were identified during our inspection are visually displayed in Appendix 6.2 and tallied in table form in Appendix 6.3. The lower stiffener weld of stiffener 16 at the north face of Girder C is fractured. The stiffener weld terminates at the end of the vertical angle leg and the crack does not extend upward into the stiffener at this location. See Figure 21 and Figure 22 for photographs of this condition. Additionally, there is (1) sheared rivet head at this location, see Figure 23. Surface corrosion was found in the interior girders (Girders B-E) primarily at the piers under the joints, see Figure 24. Surface corrosion and minor pitting (negligible section loss) was observed in the bottom of the bottom flanges of Girders B and E at the piers, see Figure 25. Some areas in the girder ends at the abutments exhibited laminar corrosion with negligible section loss, see Figure 26. Bearing stiffeners at the abutments and piers were made of double angles and had pack rust between the faying surfaces up to 1/2 inch thick, bowing the stiffener legs in some places, see Figure 27 and Figure 28. Section loss was negligible in these areas but the pack rust over time will work the angles apart from each other, further distorting the angle shape. 117 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen 10 Stiffener 62 at the north face of Girder B is deflected up to 1 inch out of plane over a 6 inch height, near the bottom 1/3 point of the stiffener, see Figure 29. 3.2 Exterior Girder Finding Details Significant corrosion was found in the exterior faces of the exterior girders (Girders A & F). These girders predominantly serve to support the sidewalk and do not see significant live loading from the travel lanes. The corrosion was laminar in form and concentrated primarily in the bottom 6 inches of the web and on the top of the exterior bottom flange. Several isolated locations have less severe laminar corrosion within the top 6 inches of the web. The laminar corrosion was present in the full length of the north exterior girder (Girder A) and primarily under the rail posts in the south exterior girder (Girder F). Upon cleaning of several of the worst areas of laminar corrosion in the webs, section loss was determined to be up to 40% in very localized areas. More typically, section loss is in the 10-30% range within the areas of corrosion. •Original web thickness = 0.49 inch •Minimum remaining web thickness = 0.29 inch (40% Section Loss) •Average remaining web thickness = 0.39 inch (20% Section Loss) The vertical web bearing stiffener of Girder F at Abutment 6 had a 2 inch diameter corrosion hole at the bottom of the stiffener adjacent to the bottom flange (100% section loss), see Figure 33. Both exterior girders had visible load sag with 3+/- inches of downward displacement near mid span locations as seen when looking along the length of the girder, see Figure 34. 118 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen 11 3.3 Girder Bearing Finding Details Bearings were in fair condition with surface corrosion throughout, see Figure 35. Some bearings had anchor bolt nuts that were backing out and/or missing lock nuts, see Figure 36. The bearing pedestal for the Girder A fixed bearing at Abutment 6 had an impending spall causing loss of bearing area, see Figure 37. The fixed bearing for Girder F at Abutment 6 was tipped away from the abutment, bending the anchor bolt, see Figure 38. Several of the grout pads at the piers had minor deterioration with no reduction to bearing area. 3.4 Diaphragms Diaphragms between exterior girders and interior girders consist of rolled C-Channels. Diaphragms between interior girders were made up of a series of steel angles and plates in the form of cross bracing. Diaphragms located away from piers were in overall good condition. Cross bracing between interior girders at pier locations typically have areas of surface corrosion. The C-Channel diaphragms between the exterior and interior girders at piers had laminar corrosion with 10-30% section loss of the webs. 119 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen 12 4.0 MAINTENANCE RECOMMENDATIONS The following recommendations have been made with the intent to extend the life of the steel girders and reduce the likelihood of tack weld crack propagation into the structural steel members. Completing the tack weld removal recommendations would limit the possibility of fatigue cracking in the steel girders. This could be a viable avenue to reduce the frequency of hands-on inspection of the girders in the future. •Clean and paint exterior girders. •Clean and paint portions of interior girders where surface corrosion has initiated through paint. •Remove cracked tack welds that are considered to not be self-arrested (see Appendix 6.2 and Appendix 6.3 for location details). •Remove all tack welds from structure if funds allow to avoid future close-proximity monitoring at higher frequencies. •Continue to monitor tack welds during future routine bridge inspections until they can be removed. 5.0 CONCLUSION The superstructure of H-09-B (Castle Creek Bridge) was confirmed to be in fair condition with NBI Item 59 = 5 after completion of the in-depth superstructure investigation. Many tack weld cracks were found to have been cracked through and self-arrested. Several locations were found to have incomplete tack weld cracks where future propagation/extension of the crack may occur. None of these locations were found to have cracks propagating into the base metal of the girder section. The structure should continue to be accessed via under bridge inspection truck during routine inspections in order to closely monitor tack welds that are cracked but not self-arrested as well as the development of new tack weld cracks. 120 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen A6.1.1 6.0 APPENDICES 6.1 PHOTO LOG 121 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen A6.1.2 Figure 1: South Elevation Figure 2: General Superstructure of Spans 1 & 2 122 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen A6.1.3 Figure 3: General Superstructure of Spans 3, 4, & 5 Figure 4: Span 1 Underdeck, Looking West 123 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen A6.1.4 Figure 5: Span 2 Underdeck, Looking West Figure 6: Span 3 Underdeck, Looking West 124 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen A6.1.5 Figure 7: Span 4 Underdeck, Looking West Figure 8: Span 5 Underdeck, Looking East 125 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen A6.1.6 Figure 9 :Typical Stiffener Tack Weld Configuration with Crack Code Call-Outs Figure 10: NSA Cracked Tack Weld – Girder B South Face – Stiffener 19 to Horizontal Leg of Top Flange Angle TWC-TFTWC-TF TWC-TF TWC-W TWC-W Tack weld between vertical leg of top flange and web (rarely seen) 126 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen A6.1.7 Figure 11: SA Cracked Tack Weld – Girder B South Face – Stiffener 17 to Horizontal Leg of Top Flange Angle Figure 12: NSA Cracked Tack Weld – Girder C North Face – Stiffener 105 to Vertical Leg of Top Flange Angle 127 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen A6.1.8 Figure 13: NSA Cracked Tack Weld – Girder D North Face – Stiffener 97 to Vertical Leg of Top Flange Angle Figure 14: NSA Cracked Tack Weld – Girder E North Face – Stiffener 107 to Vertical Leg of Top Flange Angle 128 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen A6.1.9 Figure 15: SA Cracked Tack Weld – Girder C South Face – Stiffener 16 to Vertical Leg of Top Flange Angle Figure 16: SA Cracked Tack Welds – Girder B South Face – Stiffener 41 to Vertical Leg of TF Angle and Web 129 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen A6.1.10 Figure 17: NSA Cracked Tack Weld – Girder E South Face – Stiffener 55 to Web Figure 18: NSA Cracked Tack Weld – Girder C North Face – Stiffener 109 to Web 130 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen A6.1.11 Figure 19: SA Cracked Tack Welds – Girder C North Face – Stiffener 26 to Vertical Leg of Bottom Flange and Web Figure 20: Partially Ground Out Tack Weld – Girder C South Face – Girder Top Flange to Web At Stiffener 16 131 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen A6.1.12 Figure 21: Fractured Stiffener 16 Weld – Girder C North Face at Bottom - Left Figure 22: Fractured Stiffener 16 Weld – Girder C North Face at Bottom – Right 132 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen A6.1.13 Figure 23: Sheared Rivet Head – Girder C North Face at Stiffener 16 Near Bottom Figure 24: Typical Surface Corrosion of Interior Girder at Pier – Girder E South Face at Pier 4 133 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen A6.1.14 Figure 25: Surface Corrosion and Minor Pitting in Bottom of Bottom Flange of Girder E at Pier 4 Figure 26: Laminar Corrosion of Girder E End at Abutment 6 134 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen A6.1.15 Figure 27: Typ. Pack Rust between Bearing Stiffeners of Int. Girders at Pier – Girder E S. Face at P4 – Stiffener 69 Figure 28: Typ. Pack Rust between Bearing Stiffeners of Int. Girders at Abut. – Girder B N. Face at A1 – Stiffener 1 135 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen A6.1.16 Figure 29: Deflection of Stiffener 62 at North Face of Girder B Figure 30: Laminar Corrosion in Web and Top of Bottom Flange of North Exterior Girder A 136 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen A6.1.17 Figure 31: Laminar Corrosion in Top of Web of North Exterior Girder A Figure 32: Laminar Corrosion in Web of South Exterior Girder F 137 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen A6.1.18 Figure 33: Corrosion Hole in Base of Bearing Stiffener – Girder F at Abutment 6 Figure 34: Load Sag of North Exterior Girder A 138 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen A6.1.19 Figure 35: Typical Surface Corrosion of Bearing at Pier – Girder B at Pier 1 Figure 36: Typical Anchor Bolt Nut Backed Out and Missing Lock Nut – Girder B at Pier 2 139 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen A6.1.20 Figure 37: Impending Spall of Bearing Pedestal of Girder A at Abutment 6 Figure 38: Tilted Bearing of Girder F at Abutment 6 140 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen A6.2.1 6.2 DEFECT DRAWINGS 141 142 143 144 145 146 H-09-B (Castle Creek Bridge) 11/30/2023 In-Depth Superstructure Investigation Report City of Aspen A6.3.1 6.3 TALLY SHEET 147 TWC-W TWC-BF TWC-TF -R * See Notes North Face Notes South Face Notes North Face Notes South Face Notes North Face Notes South Face Notes North Face Notes South Face Notes 1 (Abut 1)See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener 2 TWC-TF-R TWC-TF-R 3 TWC-TF-R TWC-TF-R TWC-TF-R TWC-W-R See Notes TWC-TF-R, TWC-W-R, TWC- BF-R 4 See Notes TWC-TF, TWC-W-R 5 TWC-W-R See Notes TWC-TF-R, TWC-W-R 6 See Notes TWC-W-R, TWC-BF*See Notes TWC-TF, TWC-BF TWC-TF 7 See Notes TWC-TF-R, TWC-BF TWC-BF-R TWC-W-R TWC-W-R See Notes TWC-TF-R. TWC-W-R. TWC- BF-R 8 TWC-W-R TWC-W-R TWC-W-R TWC-W-R 9 TWC-W-R See Notes TWC-W-R, TWC-BF-R TWC-W-R TWC-BF-R TWC-W-R TWC-W-R 10 TWC-BF-R See Notes TWC-W-R, TWC-BF TWC-TF-R TWC-BF-R 11 TWC-TF See Notes TWC-W-R, TWC-BF*See Notes TWC-TF, TWC-W-R, TWC-BF See Notes TWC-W, TWC-BF TWC-TF See Notes TWC-TF, TWC-W, TWC-BF See Notes TWC-TF, TWC-W-R 12 TWC-TF*TWC-W-R TWC-W-R TWC-BF-R TWC-TF TWC-W-R 13 TWC-TF TWC-TF See Notes TWC-TF, TWC-W-R TWC-TF-R TWC-W-R TWC-W-R 14 TWC-W TWC-TF TWC-BF TWC-TF TWC-W-R 15 TWC-TF TWC-W-R TWC-BF TWC-W-R 16 TWC-TF See Notes TWC-W-R, TWC-BF, Cracked stiffener weld at bottom See Notes TWC-TF, TWC-W, TWC-BF See Notes TWC-TF, TWC-W, TWC-BF TWC-TF See Notes TWC-TF, TWC-W 17 TWC-TF TWC-BF-R TWC-BF See Notes TWC-TF, TWC-BF See Notes TWC-TF, TWC-W, TWC-BF See Notes TWC-TF*, TWC-W, TWC-BF 18 TWC-W-R TWC-W-R TWC-TF See Notes TWC-TF, TWC-W, TWC-BF 19 TWC-TF*See Notes TWC-TF-R, TWC-W-R TWC-W-R See Notes TWC-TF, TWC-W TWC-TF 20 See Notes Possible TWC-TF See Notes TWC-TF-R, TWC-W-R, TWC- BF* 21 (Pier 2)See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener 22 TWC-W-R See Notes TWC-TF, TWC-W 23 TWC-TF TWC-TF TWC-TF TWC-TF*See Notes TWC-TF, TWC-W 24 TWC-W-R TWC-TF TWC-TF 25 26 TWC-TF*See Notes TWC-W, TWC-BF See Notes TWC-W, TWC-BF 27 TWC-TF TWC-BF-R TWC-TF* 28 See Notes TWC-TF, TWC-W-R TWC-W-R TWC-TF 29 TWC-W-R TWC-BF-R 30 TWC-W-R TWC-W-R TWC-W-R 31 See Notes TWC-TF, TWC-W-R TWC-TF See Notes TWC-TF, TWC-W-R See Notes TWC-TF, TWC-W, TWC-BF See Notes TWC-TF-R, TWC-W-R, TWC- BF 32 See Notes TWC-TF-R, TWC-W-R, TWC- BF-R 33 See Notes TWC-TF, TWC-W-R See Notes TWC-W-R, TWC-BF-R 34 TWC-W-R TWC-TF See Notes TWC-W, TWC-BF-R TWC-W-R 35 TWC-W-R 36 TWC-W*See Notes TWC-TF, TWC-W, TWC-BF See Notes TWC-TF, TWC-W See Notes TWC-TF, TWC-W*, TWC-BF See Notes TWC-TF, TWC-W, TWC-BF 37 TWC-TF TWC-W-R 38 See Notes Possible TWC-BF*TWC-W-R TWC-W-R 39 See Notes Possible TWC-BF*TWC-W-R TWC-BF-R TWC-TF 40 TWC-TF TWC-W-R See Notes TWC-TF, TWC-W-R 41 See Notes TWC-TF, TWC-W See Notes TWC-TF, TWC-BF TWC-W-R See Notes TWC-TF, TWC-BF TWC-TF See Notes TWC-TF, TWC-W 42 TWC-BF 43 TWC-TF TWC-TF TWC-BF TWC-W-R 44 TWC-TF TWC-W-R TWC-TF TWC-TF TWC-TF 45 (Pier 3)See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener Add on asterisk in order to indicate a TWC that has not self-arrested Code Legend Tack Weld Crack - Web to Stiffener Tack Weld Crack - Bottom Flange to Stiffener Tack Weld Crack - Top Flange to Stiffener Add on -R in order to indicate a repaired TWC See notes for atypical situations and locations where multiple defects are present Defect Stiffener #Girder B Girder C Girder D Girder E SPAN 1SPAN 2148 North Face Notes South Face Notes North Face Notes South Face Notes North Face Notes South Face Notes North Face Notes South Face Notes 46 TWC-TF TWC-BF* 47 TWC-TF-R TWC-TF 48 TWC-W-R 49 50 TWC-TF See Notes TWC-TF, TWC-W, TWC-BF See Notes TWC-W, TWC-BF See Notes TWC-W-R, TWC-BF See Notes TWC-TF, Possible TWC-W*See Notes TWC-TF, TWC-W-R TWC-BF-R 51 TWC-BF-R See Notes TWC-W-R, TWC-BF-R 52 See Notes TWC-TF, TWC-W-R 53 TWC-W-R 54 See Notes TWC-W, TWC-BF TWC-W-R TWC-W-R 55 See Notes TWC-W, TWC-BF See Notes TWC-TF-R, TWC-W-R, TWC- BF-R See Notes TWC-TF, TWC-W, TWC-BF TWC-W-R TWC-W* 56 TWC-BF-R TWC-TF-R TWC-W-R TWC-W-R TWC-W-R See Notes (2) TWC-W-R 57 TWC-BF-R TWC-TF-R TWC-W-R TWC-W-R See Notes TWC-TF-R, TWC-W-R, TWC- BF-R 58 See Notes TWC-W-R, TWC-BF* 59 See Notes TWC-TF, TWC-W, TWC-BF See Notes TWC-W-R, TWC-BF*TWC-W See Notes TWC-W, TWC-BF See Notes TWC-TF, TWC-W 60 61 TWC-W-R TWC-W-R 62 See Notes Deflected up to 1" out of plane over 6" height TWC-W TWC-W-R 63 64 TWC-W-R TWC-W-R TWC-W-R See Notes TWC-TF, TWC-W TWC-BF TWC-TF 65 66 TWC-BF TWC-W-R TWC-TF TWC-W-R 67 TWC-BF-R TWC-TF TWC-W-R 68 TWC-W-R TWC-TF 69 (Pier 4)See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes TWC-W-R, Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener 70 71 TWC-W-R TWC-W-R 72 TWC-TF-R TWC-TF-R See Notes TWC-W-R, TWC-BF-R TWC-W-R TWC-TF 73 TWC-W-R TWC-BF*See Notes (2) TWC-W, TWC-BF*TWC-W-R See Notes TWC-W, TWC-BF See Notes TWC-TF, TWC-W*TWC-W*See Notes TWC-TF, TWC-W 74 TWC-W-R TWC-BF-R TWC-W-R TWC-W-R TWC-W 75 TWC-W-R 76 TWC-TF-R TWC-BF-R See Notes TWC-TF, TWC-W-R 77 See Notes TWC-TF-R, TWC-BF-R See Notes TWC-W-R, TWC-BF TWC-W-R 78 TWC-W-R See Notes TWC-TF, TWC-W TWC-BF-R See Notes TWC-W, TWC-BF See Notes TWC-W, TWC-BF TWC-BF TWC-W-R See Notes TWC-TF, TWC-W, TWC-BF-R 79 TWC-W-R TWC-BF-R 80 TWC-TF-R See Notes TWC-TF-R, TWC-W-R TWC-BF 81 TWC-W-R TWC-W-R See Notes (2) TWC-W-R 82 See Notes TWC-TF-R, TWC-W-R 83 TWC-W-R TWC-W-R See Notes TWC-W, TWC-BF*See Notes TWC-W, TWC-BF See Notes TWC-W, TWC-BF See Notes TWC-TF, TWC-W-R 84 TWC-TF-R TWC-TF-R TWC-BF-R 85 TWC-BF*TWC-BF-R TWC-BF-R 86 See Notes TWC-TF, TWC-W-R See Notes TWC-TF, TWC-W-R TWC-W-R 87 TWC-W-R 88 TWC-BF See Notes TWC-TF, TWC-W, TWC-BF See Notes TWC-TF, TWC-W, TWC-BF TWC-W-R See Notes TWC-TF, TWC-W 89 90 TWC-W-R TWC-TF-R 91 92 TWC-TF-R 93 (Pier 5)See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener 94 95 96 TWC-TF 97 TWC-TF*TWC-TF 98 See Notes (2) TWC-W-R TWC-TF See Notes TWC-W-R, TWC-BF See Notes TWC-W, TWC-BF*TWC-TF*See Notes (2) TWC-W-R 99 100 101 TWC-W* 102 See Notes TWC-TF, TWC-W, TWC-BF 103 TWC-TF See Notes Possible TWC-W*, TWC-BF See Notes TWC-TF, TWC-W-R, TWC-BF TWC-W 104 105 See Notes TWC-TF*, TWC-W See Notes TWC-TF, TWC-W-R 106 107 See Notes Possible TWC-W*TWC-TF TWC-TF*TWC-TF* 108 TWC-TF See Notes TWC-TF, TWC-W See Notes TWC-TF, TWC-W, TWC-BF 109 TWC-W* 110 111 TWC-W*TWC-TF* 112 TWC-TF 113 (Abut 6)See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffener See Notes Pack rust between faying surfaces of bearing stiffenerSPAN 5Defect Stiffener #Girder B Girder C Girder D Girder E SPAN 3SPAN 4149 Appendix C Rehabilitation Sufficiency Rating Calculation 150 Bridge: H-09-B Description:Rehabilitation of the existing two-lane bridge Bridge Sufficiency Rating Ref: 'Recording and Coding Guide for the Structural Inventory and Appraisal of the Nation's Bridges', Report No. FHWA-PD-96-001 Each Factor uses the following data items for the calculation, denoted by the Item Number used in the inspection report: 1. STRUCTURAL ADEQUACY AND SAFETY 3. ESSENTIALITY FOR PUBLIC USE 59 Superstructure 19 Detour Length 29 ADT 60 Substructure 29 ADT 62 Culvert 100 STRAHNET Designation 66 Inventory Rating S3 = 15% Max S1 = 55% Max 4. SPECIAL REDUCTIONS 2. SERVICEABILITY AND FUNCTIONAL OBSOLESCENCE 19 Detour Length 28 Lanes on Structure 36 Traffic Safety Features 29 ADT 43 Structure Type, Main 32 Appr. Roadway Width S4 = 13% Max 43 Structure Type, Main 51 Bridge Roadway Width 53 VC over Deck 58 Deck Condition 67 Structural Evaluation 68 Deck Geometry 69 Underclearances 71 Waterway Adequacy 72 Appr. Rdwy. Aliignment 100 STRAHNET Designation S2 = 30% Max Input from Structural Inventory and Appraisal (SI&A) Sheet Item Description Input SI Units Note 19 Detour Length 0.6 mi 0.97 km 28A Lanes on Structure 2 29 ADT 25000 32 Approach Roadway Width 44.00 ft 13.41 m 36A Bridge Railings 1 Assumed value after rehab 36B Transitions 1 Assumed value after rehab 36C Approach Guardrail 1 Assumed value after rehab 36D Approach Guardrail Ends 1 Assumed value after rehab 42A Type of Service On Bridge 5 42B Type of Service Under Bridge 6 43A Structure Type Main: Matl 4 43B Structure Type Main: Type 3 51 Bridge Width Curb to Curb 27.00 ft 8.23 m 53 Min Clr Over Bridge 99.99 ft 30.48 m 58 Deck Condition 6 Assumed value after rehab 59 Superstructure Condition 6 Assumed value after rehab 60 Substructure Condition 6 Assumed value after rehab 66 Inventory Rating 24.60 T 22.3 t 67 Structural Evaluation 6 Assumed value after rehab 68 Deck Geometry 3 69 Underclearances Vert/Hor 3 71 Waterway Adequacy 9 72 Approach Road Alignment 8 100 Defense (STRAHNET) 0 SUFFICIENCY RATING = S1 + S2 + S3 - S4 151 Bridge: H-09-B Description:Rehabilitation of the existing two-lane bridge a. Only the lowest rating code of Item 59 and 60 applies Item 59 (Superstructure Condition) = 6 Item 60 (Substructure Condition) = 6 Item 62 (Culvert Condition) = 99 if "N", use 99 Controlling Condition Rating = 6 A = 0.0% b. Reduction for Load Capacity: Item 66 (Inventory Rating) = 22.3 B = 10.4% S1 = 55 - (A + B) S1 = 44.6% a. Rating Reductions (13% maximum). Item 58 (Deck Condition) = 6 A = 0% Item 67 (Structural Evaluation) = 6 B = 0% Item 68 (Deck Geometry) = 3 C = 4% Item 69 (Underclearances) = 3 D = 4% Item 71 (Waterway Adequacy) = 9 E = 0% Item 72 (Appr. Rd. Alignment) = 8 F = 0% J = A + B + C + D + E + F J = 8% b. Width of Roadway Insufficiency (15% maximum) X = ADT / #Lanes = 12500 Y = Width / #Lanes = 4.11 (1) If Item 51 (Bridge Width) + 0.6 m < Item 31 (Approach Rdwy Width) then G = 5% 8.2296+0.6= 8.83 < 13.41 G = 5% (2) For 1-lane bridges only Item 28A (Lanes on Structure) = 2 H = NA (3) For 2 or more lane bridges; If these limits apply, do not continue to (4); If Lanes = 2 and Y ≥ 4.9; H = 0% If Lanes = 3 and Y ≥ 4.6; H = 0% If Lanes = 4 and Y ≥ 4.3; H = 0% If Lanes ≥ 5 and Y ≥ 3.7; H = 0% Item 28A (Lanes on Structure) = 2 H = NA (4) For all except 1-lane bridges X = 12500 Y = 4.11 Case / Condition 1. Y < 2.7 and X > 50 H = 15% =15.0% H= NA 2. Y < 2.7 and X ≤ 50 H = 7.5% =7.5% H= NA 3. Y ≥ 2.7 and X ≤ 50 H = 0% =0.0% H= NA 4. 50 < X ≤ 125 and Y < 3.0 H = 15% =15.0% H= NA 5. 50 < X ≤ 125 and 3.0 ≤ Y < 4.0 H = 15(4 - Y)% =-1.7% H= NA 6. 50 < X ≤ 125 and Y ≥ 4.0 H = 0% =0.0% H= NA 7. 125 < X ≤ 375 and Y < 3.4 H = 15% =15.0% H= NA 8. 125 < X ≤ 375 and 3.4 ≤ Y < 4.3 H = 15(4.3 - Y)% =2.8% H= NA 9. 125 < X ≤ 375 and Y ≥ 4.3 H = 0% =0.0% H= NA 10. 375 < X ≤ 1350 and Y < 3.7 H = 15% =15.0% H= NA 11. 375 < X ≤ 1350 and 3.7 ≤ Y < 4.9 H = 15[(4.9 - Y) / 1.2]% =9.8% H= NA 12. 375 < X ≤ 1350 and Y ≥ 4.9 H = 0% =0.0% H= NA 13. X > 1350 and Y < 4.6 H = 15% =15.0% H= 15.0% 14. X > 1350 and 4.6 ≤ Y < 4.9 H = 15[(4.9 - Y) / 1.2]% =9.8% H= NA 15. X > 1350 and Y ≥ 4.9 H = 0% =0.0% H= NA 1. Structural Adequacy and Safety (55% maximum). 2. Serviceability and Functional Obsolescence (30% maximum) 152 Bridge: H-09-B Description:Rehabilitation of the existing two-lane bridge From (2) through (4), Use H= 15.0% G + H (15% maximum) G+H = 15.0% c. Vertical Clearance Insufficiency (2% maximum) If Item 100 (STRAHNET Highway) > 0 and Item 53 (VC over Deck) ≥ 4.87; I = 0% Item 53 (VC over Deck) < 4.87; I = 2% If Item 100 (STRAHNET Highway) = 0 and Item 53 (VC over Deck) ≥ 4.26; I = 0% Item 53 (VC over Deck) < 4.26; I = 2% Item 100 (STRAHNET Highway) = 0 Item 53 (Lanes on Structure) = 30.48 m I = 0.0% S2 = 30 - [ J + (G + H) + I ] S2 = 7.0% 3. Essentiality for Public Use (15% maximum) a. Determine K = (S1 + S2) / 85 K = 0.606837482 b. Calculate A = 15 [ (ADT (#29) x Detour Length (#19)) / ( 320,000 x K) ] Item 29 (ADT) = 25000 Item 19 (Detour Length) = 0.97 A = 1.9% c. STRAHNET Highway Designation: If Item 100 (STRAHNET Highway) > 0, B = 2% If Item 100 (STRAHNET Highway) = 0, B = 0% Item 100 (STRAHNET Highway) = 0 B = 0.0% S3 = 15 - (A + B) S3 = 13.1% S1 + S2 + S3 = 64.7% 4. Special Reductions (Use only with S1 + S2 + S3 ≥ 50) (13% maximum); a. Detour Length Reduction (maximum 5%) A = (#19)4 x (7.9x10-9) Item 19 (Detour Length) = 0.97 km A = 0.0% b. If the 2nd and 3rd digits of Item 43 (Structure Type, Main) are equal to 10, 12, 13 14, 15, 16 or 17, then B = 5% Item 43B Structure Type 03 B = 0.0% c. If 2 digits of Item 36 (Traffic Safety Features) = 0, C = 1% If 3 digits of Item 36 (Traffic Safety Features) = 0, C = 2% If 4 digits of Item 36 (Traffic Safety Features) = 0, C = 3% Item 36A Bridge Railings 1 Item 36B Transitions 1 Item 36C Approach Guardrail 1 Item 36D Approach Guardrail Ends 1 Total 0's 0 C = 0.0% S4 = A + B + C S4= 0.0% Sufficiency Rating = 64.7% 153 Appendix D Rehabilitation Cost Estimate 154 Bid Item Item Description Units Qty Unit Cost Total CostNote202-00055Removal of Fiber Optic CableLF551 $5.00 $2,755.00Unit cost estimated from average bid price on 2022 cost book202-00040Removal of Electrical ConduitLF551 $14.00 $7,714.00Unit cost estimated from Engineering Estimate price on 2021 cost book202-XXXXXRemoval of Other UtilitiesLF551 $10.00 $5,510.00Unit cost average of FO and electric202-00220 Removal of Asphalt Mat SY1405 $12.00 $16,865.00Asphalt overlay will be replaced with PPC overlay.202-00505Removal of Portions of Present StructureSF5507 $175.00 $963,746.88Removal limit: 6.5 feet from both edges to remove sidewalk and exterior girder202-05150 Sandblasting SF18432 $1.95 $35,942.40All structural steel. Unit Cost estimated from 2020 cost book.203-02330 Laborer HR61 $60.00 $3,630.00For Removal of NSA Tack Welds210-00530Rebuild Portions of Present StructureSF5507 $150.00 $826,068.75Rebuild limit: 6.5 feet from both edges to rebuild sidewalk and portion of deck. Only includes concrete work and pedestrian bridge rail reset.XXX-XXXXXReplace Fiber Optic CableLF551 $10.00 $5,510.00AssumedXXX-XXXXXReplace Electrical ConduitLF551 $28.00 $15,428.00AssumedXXX-XXXXX Replace Other Utilities LF551 $20.00 $11,020.00Assumed250-00100Environmental Health and SafetyLS1 $1,000,000.00 $1,000,000.00Assumed cost for lead paint removal and preparation for repainting408-01100 Joint Sealant LF240 $50.00 $12,000.00Unit cost based on 2023 cost book509-00000 Structural Steel LB91600 $5.50 $503,800.00Unit cost based on 2022 cost book512-00101 Bearing Device EA12 $4,000.00 $48,000.00Unit cost based on 2022 cost book509-90003 Paint Structural Steel LS1 $350,000.00 $350,000.00Unit cost based on 2021 cost book519-03035Place Thin Bonded Overlay (Polyester Concrete)SY1405 $135.00 $189,731.25Based on previous BPM project work. 519-03055Furnish Thin Bonded Overlay (Polyester Concrete)CF791 $205.00 $162,062.11Based on previous BPM project work. 601-03000 Concrete Class D CY1 $3,500.00 $3,500.00For bearing pedestal, Based on 2023 cost book data601-06100 Concrete (Patching) CY25 $3,500.00 $86,345.00Unit cost based on 2022 cost book606-11035Bridge Rail Type 10 MASHLF848 $340.00 $288,320.00Assume rail installed on both sides of bridge.$4,537,948.38$1,361,384.52$5,900,000.00CY = Cubic yard LS = Lump sumEA = Each NSA = Not self arrestedFO = Fiber optic SF = square feetHR = Hourly SY = square yardLF = Linear footCost Estimate SummaryTotalContingency (30%)Grand Total155 Appendix E ABC Method: Incremental Bridge Launch 156 Figure 43a. ABC Incremental Bridge Launch Layout SH82 Over Castle Creek Bridge Feasibility Study Staging Area for Girder Segments (Numbered by Sequence of Launch) CONFLICT: Existing Utilities, Including Critical Communications Fiber and Copper CONFLICT: Power Plant Road, Harbor Lane, and Trail Closed During Existing Bridge Demolition and New Bridge Launch Activities Staging Area for Girder Segments (Numbered by Sequence of Launch) Launch Pit for Girder Segments (Approx. 6' Deep x 250' Long Pit) New Support System for Utilities Existing Utilities Staging Area and Final Configuration of Girder Segments After Incremental Launch Incremental Launch – Typical Launch Sequence (Step 2 Shown) Girder Segments in Their Final Configuration Girder Segments in Launch Process (Step 2) Launch Pit for Girder Segments (Approx. 6' Deep x 250' Long Pit) 1 1 1 2 2 2 3 3 3 4 4 4 NOSE Abutment AbutmentPier 97'-6"97'-6"112'-6"112'-6" Pier Pier Abutment AbutmentPier 97'-6"97'-6"112'-6"112'-6" Pier Pier NOSE New Support System for Utilities 157 Figure 43b. ABC Incremental Bridge Launch Sequence SH82 Over Castle Creek Bridge Feasibility Study Castle Creek 420'-0" 97'-6"97'-6"112'-6"112'-6" CL CL CL CL CL Existing Grade Pier Pier Bridge Pier Harbour Lane Power Plant Road Power Plant Road Pedestrian Trail Abutment Abutment Castle Creek Existing Grade Pier Pier Bridge Pier Harbour Lane Power Plant Road Power Plant Road Pedestrian Trail Abutment Abutment Castle Creek Existing Grade Pier Pier Pier Harbour Lane Power Plant Road Power Plant Road Pedestrian Trail Abutment Abutment Castle Creek Existing Grade Pier Pier Pier Harbour Lane Power Plant Road Power Plant Road Pedestrian TrailFinished Grade Abutment Abutment Step 0 (Not Shown): Build the piers. Close the existing bridge. Demolish the existing bridge. Build the abutments. Dig the launch pit and set up launch rollers. Step 1: Set up and connect the launching nose and Segment 1 on the launch rollers. Push and launch girders forward over the first pier. Step 2: Set up Segment 2 on the launch rollers and connect to Segment 1. Push and launch girders forward over the next pier. STEP 2 STEP 3 STEP 4 Step 3: Set up Segment 3 on the launch rollers and connect to Segment 2. Push and launch girders forward over the next pier. Step 4: Set up Segment 4 on the launch rollers and connect to Segment 3. Push and launch girders forward to the abutment. Disconnect the launching nose. Replace temporary bearings with permanent bearings. Foam/pour/cure the deck, diaphragms, approaches. 1 NOSE 12 NOSE Launch Pit Launch Pit Launch Roller Launch Pit Launch Pit 123 NOSE 1234 STEP 1 Finished Grade Launch Roller Launch Roller 158 Appendix F ABC Method: Bridge Slide 159 STEP 1 STEP 2 STEP 3 STEP 4 Figure 44a. Typical ABC Bridge Slide SH82 Over Castle Creek Bridge Feasibility Study 160 CONFLICT 4 Building overtop of a residential home is extremely high risk. Contractors will not take this risk on. The risk would force a ROW acquisition of the property to use this method of ABC. CONFLICT 5 During bridge demolition and bridge slide, Power Plant Road will need closures. This eliminates the only detour route during those periods. Once the existing bridge is demolitioned, SH 82 has a full closure until end of construction, which is at least one month of time. When available, Power Plant Road will be the only detour route available during SH 82 closure. CONFLICT 3 Without traditional phasing of the bridge, the utilities would all need temporary support across the length of the bridge, or be cut off for the period of time until the bridge is slid into place. Cutting off utilities is not feasible with essential copper and fiber on this route. CONFLICT 1 The existing Gas Regulator Station building is a major conflict as this is high-pressure gas in/out in the area. CONFLICT 2 Most of the temporary pier locations conflict with existing infrastructure: Trail, Power Plant Road, Harbour Lane, or private land owners. Figure 44b. Major Con flicts to an ABC Bridge Slide SH82 Over Castle Creek Bridge Feasibility Study 161 Appendix G Replacement Phasing Options 162 Existing Substructure PHASE 1 NOTE No pedestrian accommodation is currently provided in this phase. 8'-0" Sidewalk 15'-0" Travelway SH82 WB SH82 EB Phase 1 Limits of Construction = 18'-6" 5'-9" Pedestrian 15'-0" TravelwayPhase 2 Limits of Construction = 18'-6" Phase 3 Limits of Construction = 9'-10" 15'-0" Travelway15'-0" Travelway 35'-10" Travelway 48'-10" Out to Out 10'-0" Sidewalk PHASE 2 PHASE 3 FINAL TWO LANE Rebuild the two lane + north trail layout that currently exists; eliminates the south sidewalk. SH82 WB SH82 EB Existing Substructure Existing Substructure 163 THREE LANE OPTION 1 PHASE 1 NOTE No pedestrian accommodation is currently provided in this phase. 8'-0" Sidewalk 15'-0" Travelway SH82 WB SH82 EB Phase 1 Limits of Construction = 20'-6" 5'-9" Pedestrian 17'-0" TravelwayPhase 2 Limits of Construction = 19'-8" Phase 3 Limits of Construction = 9'-10" 17'-0" Travelway16'-2" Travelway 39'-0" Travelway 52-0" Out to Out 10'-0" Sidewalk PHASE 2 PHASE 3 FINAL SH82 WB SH82 EBSH82 GP Replace with three lane + north trail layout that currently exists; eliminates the south sidewalk. Existing Substructure Existing Substructure Existing Substructure 164 THREE LANE OPTION 2 PHASE 1 NOTE This option does not accommodate pedestrians in any phase of construction. This option requires approximately 6 feet of overbuild on the bridge to minimize the time needed for using a single lane. This option has 3.8 feet of ROW impact on the south side of the bridge. 15'-0" Travelway Phase 1 Limits of Construction = 18'-6" Phase 2 Limits of Construction = 18'-11"15'-0" Travelway15'-0" Travelway 44'-11" Travelway 57-11" Out to Out 10'-0" Sidewalk PHASE 2 FINAL SH82 WB SH82 EBSH82 GP Replace with three lane + north trail layout that currently exists; eliminates the south sidewalk. Phase 1 Limits of Construction = 18'-6" SH82 WB SH82 EB Existing Substructure Existing Substructure 165 THREE LANE OPTION 3 PHASE 1 NOTE No pedestrian accommodation is currently provided in this phase. 5'-0" Sidewalk 28'-0" Travelway SH82 WB SH82 EB Phase 1 Limits of Construction = 18'-6" 26'-0" TravelwayPhase 3 Limits of Construction = 22'-0" 39'-0" Travelway 52-0" Out to Out 10'-0" Sidewalk PHASE 2 PHASE 3 FINAL SH82 WB SH82 EBSH82 GP Replace with three lane + north trail layout that currently exists; eliminates the south sidewalk. SH82 WB SH82 EB 5'-0" Sidewalk 15'-0" Travelway 15'-0" TravelwayPhase 2 Limits of Construction = 10'-0" SH82 WB SH82 EB NOTE This option requires removal of the "new" portion of the sidewalk to gain an additional 3 feet of width for construction phasing. NOTE This option has 4.6 feet of ROW impact on the south side of the bridge. Existing Substructure Existing Substructure Existing Substructure 166 Appendix H Conceptual Bridge Rehabilitation Plans 167 677+00 682+00679+00678+00 680+00 681+00 fofofofofofofofofofofofofo fofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofossssssssssssssssx x xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx $$PLOT_INFO$$All seals for this set of drawings are applied to the cover page(s) $$FILES$$ $$DATE$$ Date Comments Init. Sheet Revisions As Constructed No Revisions: Revised: Void:Sheet Subset: Detailer: Designer: Sheet Number 2023-218 Project No./CodeSH82 over Castle Creek Bridge BRIDGE Subset Sheets: of Structure Numbers Print Date: File Name: Horiz. Scale:AS NOTED H-09-B REHABILITATION - ALTERNATIVE GENERAL LAYOUT 2 ℄ Brg Abut 1 ℄ Brg Abut 6 420'-0" PLAN SCALE: 1" = 40' ELEVATION SCALE: 1" = 40' 75'-0"90'-0"90'-0"90'-0"CASTLE CREEKExisting Sidewalk BF Abut 6 ℄ Brg Abut 1 ℄ Pier 2 ℄ Brg Abut 6 ℄ Pier 3 ℄ Pier 4 420'-0" 75'-0"90'-0"90'-0"90'-0"90°0'0"(Typ)Existing Utilities (to be reset) See Note 1 BF Abut 1 EL 7910 EL 7900 EL 7890 EL 7880 EL 7870 EL 7860 EL 7850 EL 7840 EL 7830 EL 7910 EL 7900 EL 7890 EL 7880 EL 7870 EL 7860 EL 7850 EL 7840 EL 7830 ℄ Pier 2 ℄ Pier 3 ℄ Pier 4 ℄ Pier 5 ℄ SH82 BF Abut 1 Expansion Jt Finished Grade Power Plant Road Approximate Existing Grade Power Plant Road Sealed Joint at Pier, Typ Sealed Jt BF Abut 6 NOTES 1.Location of existing utilities and existing grade shown are approximate. SH82 EB To ASPEN 75'-0" 75'-0"℄ Pier 5 ℄ Brg Abut 1 Sta 677+86.00 ℄ Pier 2 Sta 678+61.00 ℄ Pier 3 Sta 679+51.00 ℄ Pier 4 Sta 680+41.00 Existing Wyoming TL3 Bridge Rail (Special) ℄ Pier 5 Sta 681+31.00 ℄ Brg Abut 6 Sta 682+06.00 LEGEND Limits of rebuild portions of present structure Existing Steel Handrail Existing Steel Handrail Existing Gas Regulator Station Existing Gas Line 27'-0"Travel Way40'-0"Out to OutAbut Footing (Below) Typ. E E E E E F Existing Castle Creek Bridge Existing Concrete Pier, Typ (Existing railing not shown for clarity) Castle Creek Shared Pedestrian/Bike Path A. BHANDARI J. PROTHERO B10 B15 Existing Approach Slab Existing Retaining Wall Pier Column and Footing (Below) Typ. Shared Pedestrian - Bike Path SH82 WB To GLENWOOD SPRINGS Approach Slab Expansion Jt Existing Wyoming TL3 Bridge Rail 168 $$PLOT_INFO$$All seals for this set of drawings are applied to the cover page(s) $$FILES$$ $$DATE$$ Date Comments Init. Sheet Revisions As Constructed No Revisions: Revised: Void:Sheet Subset: Detailer: Designer: Sheet Number 2023-218 Project No./CodeSH82 over Castle Creek Bridge BRIDGE Subset Sheets: of Structure Numbers Print Date: File Name: Horiz. Scale:AS NOTED H-09-B REHABILITATION - ALTERNATIVE CONSTRUCTION PHASING 3 Girder "A" 8'-0" Sidewalk 5'-0" Sidewalk10'-0" Phase 2 Work Limits = 18'-0" 2'-0" Shldr Phase 2 Single Traffic Lane = 11'-0"2'-0" Shldr 8'-0" Sidewalk Phase 1 Single Traffic Lane = 11'-0"2'-0" Shldr 10'-0" Phase 1 Work Limits = 15'-0" Temporary Traffic Barrier (Pinned) PHASE 1 SECTION AT BRIDGE SCALE: 1/4" = 1'-0" (Looking East) PHASE 2 SECTION AT BRIDGE SCALE: 1/4" = 1'-0" (Looking East) 27'-0" 40'-0" Steel Wide Flange Girder, Typ Steel Plate Girder, Typ Steel Angle Interior Crossframe Diaphragm, Typ Phase 1 Underbridge Work Limits 27'-0" 40'-0" 2'-0"5'-0" Sidewalk Steel Plate Girder, Typ Phase 2 Underbridge Work Limits Proposed removal and replacement LEGEND A. BHANDARI J. PROTHERO B11 B15 2'-0" Temporary Traffic Barrier (Pinned) Girder "B"Girder "C"Girder "D"Girder "E" Girder "F" Existing Utilities Girder "A" Girder "B"Girder "C"Girder "D"Girder "E" Girder "F" Existing Utilities, See Notes Steel Wide Flange Girder, Typ 2'-0" Shldr - Remove and rebuild South sidewalk and framing PHASE 1: - Existing utilites to be removed and reset and/or relocated to South side of bridge. - Remove and rebuild North sidewalk and framing PHASE 2: 23'-0" 20'-0" Steel Angle Interior Crossframe Diaphragm, Typ 169 $$PLOT_INFO$$All seals for this set of drawings are applied to the cover page(s) $$FILES$$ $$DATE$$ Date Comments Init. Sheet Revisions As Constructed No Revisions: Revised: Void:Sheet Subset: Detailer: Designer: Sheet Number 2023-218 Project No./CodeSH82 over Castle Creek Bridge BRIDGE Subset Sheets: of Structure Numbers Print Date: File Name: Horiz. Scale:AS NOTED H-09-B REHABILITATION - ALTERNATIVE TYPICAL SECTIONS 4 TYPICAL SECTION - ABUT 1 TYPICAL SECTION - ABUT 6 ℄ SH82 SCALE: 1/8" = 1'-0" (LOOKING WEST) SCALE: 1/8" = 1'-0" (LOOKING EAST) 1'-6" ℄ SH82 1'-6" 5'-0" Sidewalk 2'-6" Shdr 11'-0" EB Lane 11'-0" WB Lane 2'-6" Shdr 8'-0" Sidewalk 6'-6"8'-8"8'-8"8'-8"6'-6" Steel Wide Flange Girder, Typ Girders A & F to be replaced Steel Plate Girder, Typ Clean and Paint Girders Steel Channel/Plate Diaphragm, Typ ℄ Girder F ℄ Girder E ℄ Girder D ℄ Girder C ℄ Girder B ℄ Girder A Abutment Cap Abutment Backwall Tapered Column with Footing, Typ 8'-0" Sidewalk 2'-6" Shdr 11'-0" WB Lane 11'-0" EB Lane 2'-6" Shdr 5'-0" Sidewalk 6'-6"8'-8"8'-8"8'-8"6'-6" Steel Wide Flange Girder, Typ Girders A & F to be replaced Steel Plate Girder, Typ Clean and Paint Girders ℄ Girder A ℄ Girder B ℄ Girder C ℄ Girder D ℄ Girder E ℄ Girder F Steel Channel/Plate Diaphragm, Typ Abutment Stem and Footing Abutment Backwall ℄ SH82 1'-6"3'-0"VARIES(55'-0" at Pier 2; 63'-0" at Pier 3; 68'-0" at Pier 4; 40'-0" at Pier 5)9'-012"TYPICAL SECTION - PIERS 2, 3, 4 AND 5 SCALE: 1/8" = 1'-0" (Looking East) 8'-0" Sidewalk 2'-6" Shdr 11'-0" WB Lane 11'-0" EB Lane 2'-6" Shdr 5'-0" Sidewalk 6'-6"8'-8"8'-8"8'-8"6'-6" ℄ Girder A ℄ Girder B ℄ Girder C ℄ Girder D ℄ Girder E ℄ Girder F 33'-0"4'-0"Steel Wide Flange Girder, Typ Girders A & F to be replaced Steel Plate Girder, Typ Clean and Paint Girders Steel Angle Diaphragm, Typ Pier Cap 1'-8" x 4'-0" Concrete Diaphragm Tapered Column and Footing, Typ Approximate Limits of Concrete Repair at Piers caps. Approx 10% per Pier Cap LEGEND Expansion Rocker Bearing, Typ Clean and Repair all bearings at all piers. Remove and replace grout bearing pads where necessary. Replace nuts and bolts and reset pins as necessary. (Typ) Expansion Rocker Bearing, Typ Replace all Bearings at Abutment 1 Fixed Bearings, Typ Replace all Bearings at Abutment 6 B12 B15 6" 40'-0" 6" Abutment Seat Finished Grade Finished Grade Abutment Seat 6" 40'-0" 6" Remove Soil and Debris from around Bearings, Typ 6" 40'-0" 6" 3'-6" Typ A. BHANDARI J. PROTHERO Existing Utilities to be removed and reset or relocated Existing Utilities to be removed and reset or relocated Large Cracks in Girder "A" Abutment Seat Repair/Rebuild Concrete Seat. 170 679+00678+00 $$PLOT_INFO$$All seals for this set of drawings are applied to the cover page(s) $$FILES$$ $$DATE$$ Date Comments Init. Sheet Revisions As Constructed No Revisions: Revised: Void:Sheet Subset: Detailer: Designer: Sheet Number 2023-218 Project No./CodeSH82 over Castle Creek Bridge BRIDGE Subset Sheets: of Structure Numbers Print Date: File Name: Horiz. Scale:AS NOTED H-09-B REHABILITATION - ALTERNATIVE FRAMING PLAN 1 OF 2 5 ℄ Brg Abut 1 ℄ Pier 2 ℄ Pier 3 4 Spa at 18'-9" = 75'-0"15'-0"2 Spa at 18'-9" = 37'-6"7'-6" A B C D E F 75'-0" SPAN 1 90'-0" SPAN 2 90'-0" SPAN 3 ℄ Bridge Edge of Deck Diaphragm Spacing 1 KEY NOTES Pack rust between faying surfaces of angle legs, up to 12" thick, typical at bearing stiffener locations. Cracked stiffener weld at bottom.2 CODE LEGEND TWC-W TACK WELD CRACK - WEB TO STIFFENER TWC-BF TACK WELD CRACK - BOTTOM FLANGE TO STIFFENER TWC-TF TACK WELD CRACK - TOP FLANGE TO STIFFENER ADD-ON CODES: * NOT SELF ARRESTED -P POSSIBLE CRACK PARTIAL FRAMING PLAN SCALE: 1" = 15' 1 2 1 TWC-BF * TWC-TF * TWC-BF * TWC-TF * TWC-TF * TWC-TF * TWC-TF * TWC-BF * TWC-W * TWC-BF * -P TWC-BF * -P TWC-W * TWC-W * - P TWC-W * GIRDER FACE VIEW TWC-TF TWC-TFTWC-TF TWC-W TWC-W TWC-BF TWC-BF TWC-W TWC-W A. BHANDARI J. PROTHERO B13 B15 TWC-TF * 4 Spa at 18'-9" = 75'-0" TWC-BF * 15'-0"Splice Location 1 15'-0"Splice Location ℄ SH82 Interior Crossframe Diaphragm, Typ End Channel Diaphragm at Support, Typ Edge of Deck NOTE:Not all girder defects shown. Only tack weld cracks that are NOT self-arresting (NSA) are noted. All NSA welds shall be repaired at a minimum to improve the service life of the steel plate girders. 171 682+00680+00 681+00 $$PLOT_INFO$$All seals for this set of drawings are applied to the cover page(s) $$FILES$$ $$DATE$$ Date Comments Init. Sheet Revisions As Constructed No Revisions: Revised: Void:Sheet Subset: Detailer: Designer: Sheet Number 2023-218 Project No./CodeSH82 over Castle Creek Bridge BRIDGE Subset Sheets: of Structure Numbers Print Date: File Name: Horiz. Scale:AS NOTED H-09-B REHABILITATION - ALTERNATIVE FRAMING PLAN 2 OF 2 6 ℄ Pier 4 ℄ Pier 5 7'-6"2 Spa at 18'-9" = 37'-6"15'-0"4 Spa at 18'-9" = 75'-0" A B C D E F ℄ Brg Abut 6℄ Bridge Edge of Deck Diaphragm Spacing 90'-0" SPAN 3 90'-0" SPAN 4 75'-0" SPAN 5 2 KEY NOTES Pack rust between faying surfaces of angle legs, up to 12 " thick, Typ at bearing stiffener locations. Stiffener deflected, up to 1" out of plane over 6" height, near bottom 13 point. CODE LEGEND TWC-W TACK WELD CRACK - WEB TO STIFFENER TWC-BF TACK WELD CRACK - BOTTOM FLANGE TO STIFFENER TWC-TF TACK WELD CRACK - TOP FLANGE TO STIFFENER ADD-ON CODES: * NOT SELF ARRESTED -P POSSIBLE CRACK PARTIAL FRAMING PLAN SCALE: 1" = 15' GIRDER FACE VIEW TWC-TF TWC-TFTWC-TF TWC-W TWC-W TWC-BF TWC-BF TWC-W TWC-W 2 TWC-BF * TWC-BF * TWC-BF * TWC-BF * TWC-W * TWC-W * TWC-BF * TWC-BF * TWC-TF *TWC-BF * TWC-TF * TWC-W * TWC-W * - P TWC-TF * TWC-W * - P TWC-W *TWC-W * TWC-TF * TWC-TF *TWC-TF * 1 1 1 15'-0"Splice Location 15'-0"Splice Location 4 Spa at 18'-9" = 75'-0" Edge of Deck ℄ SH82 Interior Crossframe Diaphragm, Typ End Channel Diaphragm at Support, Typ 1 NOTE:Not all girder defects shown. Only tack weld cracks that are NOT self-arresting (NSA) are noted. All NSA welds shall be repaired at a minimum to improve the service life of the steel plate girders. A. BHANDARI J. PROTHERO B14 B15 172 $$PLOT_INFO$$All seals for this set of drawings are applied to the cover page(s) $$FILES$$ $$DATE$$ Date Comments Init. Sheet Revisions As Constructed No Revisions: Revised: Void:Sheet Subset: Detailer: Designer: Sheet Number 2023-218 Project No./CodeSH82 over Castle Creek Bridge BRIDGE Subset Sheets: of Structure Numbers Print Date: File Name: Horiz. Scale:AS NOTED H-09-B REHABILITATION - ALTERNATIVE REPAIR DETAIL NOTES 7 Clean, repaint, and regrout bearings at piers where necessary. Replace loose nuts and bolts where necessary. (Typical of all bearings at piers) Concrete Repair of Bearing pedestal at Abutment 6, Girder A Partial removal and reconstruction of pedestal due to extents of defects Grind out all Non Self-Arresting (NSA) Tack Welds Clean and Repaint all Structural Steel TYPICAL EXPANSION ROCKER BEARING AT PIER ABUTMENT 6-SUPPORT PEDESTAL AT GIRDER "A" Girder "B" (Beyond) Fixed Bearing Girder "A" Backwall A. BHANDARI J. PROTHERO B15 B15 Stiffener Existing Crack in Tack Weld Girder Web TYPICAL STIFFENER TACK WELD STEEL GIRDER SUPERSTRUCTURE 173 Appendix I Conceptual Two-lane Bridge Replacement Plans 174 $$PLOT_INFO$$All seals for this set of drawings are applied to the cover page(s) $$FILES$$ $$DATE$$ Date Comments Init. Sheet Revisions As Constructed No Revisions: Revised: Void:Sheet Subset: Detailer: Designer: Sheet Number 2023-218 Project No./CodeSH82 over Castle Creek Bridge BRIDGE Subset Sheets: of Structure Numbers Print Date: File Name: Horiz. Scale:AS NOTED H-09-B GENERAL NOTES 1B01 The existing bridge is a 5 span (75'-0", 90'-0", 90'-0', 90'-0", and 75'-0") continuous steel girder bridge over Power Plant Road, Castle Creek, and Harbour Lane. 8'-0" north sidewalk and 5'-0" south sidewalk, 27'-0" roadway, Wyoming TL3 Bridge Rail, and (2) Side-Mounted Bridge Rails. Rehabilitation work considered includes, bearing replacement and repair, bearing pedestal replacement at Abut 6, exterior girder replacement, steel painting, tack weld removal, concrete repairs for deck and pier caps, joint sealant replacement, and bridge rail repair. 2-Lane replacement considers replacement of the existing bridge with a 4 span (97'-6", 97'-6", 112'-6", and 112'-6") continuous post-tensioned CIP box girder bridge. 10'-0" sidewalk, 36'-0" roadway, and (2) 1'-6" Type 9 Bridge Rails. 3-Lane replacement considers replacement of the existing bridge with a 4 span (97'-6", 97'-6", 112'-6", and 112'-6") continuous post-tensioned CIP box girder bridge. 10'-0" sidewalk, 39'-0" roadway, and (2) 1'-6" Type 9 Bridge Rails. Phased construction assumed for all alternatives. See "SH82 over Castle Creek Bridge Feasibility Study" for additional information. GENERAL NOTES AASHTO, 9th Edition LRFD with current interims Design Method: Load and Resistance Factor Design Live Load:HL-93 (design truck or tandem, and design lane load) Dead Load: Assumes 36 psf for bridge deck overlay Assumes 5 psf for permanent deck forms Reinforced Concrete: Class D Concrete:f'c = 4,500 psi Reinforcing Steel:f'y = 60,000 psi Drilled Shaft Concrete: Class BZ Concrete:f'c = 4,000 psi Reinforcing Steel:fy = 60,000 psi Structural Steel: AASHTO M270 (ASTM A709) Grade 36fy = 36,000 psi AASHTO M270 (ASTM A709) Grade 50fy = 50,000 psi Post-Tensioned concrete: Class S concrete f'c = (see details) f's = 270,000 psi DESIGN DATA B01 GENERAL INFORMATION B10 REHABILITATION - GENERAL LAYOUT B11 REHABILITATION - ALTERNATIVE TYPICAL SECTION 1 OF 2 B12 REHABILITATION - ALTERNATIVE TYPICAL SECTION 2 OF 2 B13 REHABILITATION - FRAMING PLAN 1 OF 2 B14 REHABILITATION - FRAMING PLAN 2 OF 2 B15 REHABILITATION - REPAIR DETAIL NOTES 1 OF 2 B16 REHABILITATION - REPAIR DETAIL NOTES 2 OF 2 B20 REPLACEMENT - 2 LANE ALTERNATIVE GENERAL LAYOUT B21 REPLACEMENT - 2 LANE ALTERNATIVE TYPICAL SECTION B22 REPLACEMENT - 2 LANE ALTERNATIVE CONSTRUCTION PHASING (1 OF 3) B23 REPLACEMENT - 2 LANE ALTERNATIVE CONSTRUCTION PHASING (2 OF 3) B24 REPLACEMENT - 2 LANE ALTERNATIVE CONSTRUCTION PHASING (3 OF 3) B30 REPLACEMENT - 3 LANE ALTERNATIVE GENERAL LAYOUT B31 REPLACEMENT - 3 LANE ALTERNATIVE TYPICAL SECTION B32 REPLACEMENT - 3 LANE ALTERNATIVE CONSTRUCTION PHASE (1 OF 3) B33 REPLACEMENT - 3 LANE ALTERNATIVE CONSTRUCTION PHASE (2 OF 3) B34 REPLACEMENT - 3 LANE ALTERNATIVE CONSTRUCTION PHASE (3 OF 3) INDEX OF DRAWINGS X BXX (Per M-100-2 or as shown below) Ea = Each BF = Back Face FF = Front Face FFBW = Front Face Backwall RC = Reinforced Concrete WSEL = Water Surface Elevation EB = Eastbound WB = Westbound GP = General Purpose Abut = Abutment Sta = Station Typ.= Typical E = Expansion Bearing F = Fixed Bearing ABBREVIATIONS View/Photo Identification Section, Detail, or View Identification Cross Reference Drawing Number (if blank or dash, reference is to same sheet)REHABILITATION2 - LANEREPLACEMENT3 - LANEREPLACEMENTS. SOWAL A.PRICE 175 677+00 682+00679+00678+00 680+00 681+00 fofofofofofofofofofofofofo fofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofossssssssssssssssx x xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx $$PLOT_INFO$$All seals for this set of drawings are applied to the cover page(s) $$FILES$$ $$DATE$$ Date Comments Init. Sheet Revisions As Constructed No Revisions: Revised: Void:Sheet Subset: Detailer: Designer: Sheet Number 2023-218 Project No./CodeSH82 over Castle Creek Bridge BRIDGE Subset Sheets: of Structure Numbers Print Date: File Name: Horiz. Scale:AS NOTED H-09-B REPLACEMENT - 2 LANE ALTERNATIVE GENERAL LAYOUT 8B20 B24 ℄ Brg Abut 1 ℄ Pier 2 ℄ Brg Abut 5℄ Pier 3 ℄ Pier 4 420'-0" PLAN SCALE: 1" = 40' ELEVATION SCALE: 1" = 40' 97'-6"97'-6"112'-6"112'-6"CASTLE CREEKExisting Structure H-09-B (to be removed) BF Abut 5 ℄ Brg Abut 1 ℄ Pier 2 ℄ Brg Abut 5 ℄ Pier 3 ℄ Pier 4 420'-0" 97'-6"97'-6"112'-6"112'-6"48'-10"Out to Out24'-512"24'-412"1'-6" Bridge2 Lanes @ 11'-0"= 22'-0"6'-11"±6'-11"±1'-6" Bridge90°0'0"(Typ)N74°23'29"W Existing Utilities (to be reset) See Note 2 Proposed Structure BF Abut 1 20'-0" Approach Slab (Typ)ShldrShldrRail Type 9Rail Type 9Sdwlk7910 7900 7890 7880 7870 7860 7850 7840 7830 ℄ SH82 See Note 1 BF Abut 1 Expansion Jt Finished Grade E Power Plant Road Existing Grade See Note 3 Power Plant Road Castle Creek Harbour Lane Sleeper Slab (Typ) Expansion Jt Approach Slab (Typ) BF Abut 5 E NOTES 1.Existing SH82 alignment shown. 2.Existing utility locations are approximate. 3.Existing grade is approximate. SH82 EB to ASPEN FFF 7910 7900 7890 7880 7870 7860 7850 7840 7830 Pedestrian Trail C Power Plant RoadL C Harbour LaneL SH82 WB to GLENWOOD SPRINGS C Power Plant RoadL Existing Structure H-09-B (to be removed)10'-0"S. SOWAL A.PRICE 176 $$PLOT_INFO$$All seals for this set of drawings are applied to the cover page(s) $$FILES$$ $$DATE$$ Date Comments Init. Sheet Revisions As Constructed No Revisions: Revised: Void:Sheet Subset: Detailer: Designer: Sheet Number 2023-218 Project No./CodeSH82 over Castle Creek Bridge BRIDGE Subset Sheets: of Structure Numbers Print Date: File Name: Horiz. Scale:AS NOTED H-09-B REPLACEMENT - 2 LANE ALTERNATIVE TYPICAL SECTION 10 TYPICAL SECTION SCALE: 1/4" = 1'-0" (Looking East, at Pier) 48'-10" Out to Out 6'-11"± Shldr2 Lanes @ 11'-0" = 22'-0"6'-11" ± Shldr10'-0" Sidewalk 24'-412"24'-512" 1'-6" Bridge Rail 1'-6" Bridge Rail ℄ SH82 Type 9 Type 9 2 - 2"Ø Electrical Conduit for Future use (Typ) Reset Existing Utilities Post-Tensioned Cast-in-Place Concrete Box Girder Structural Concrete Stain (Typ) 2.00%2.00% SH82 EBSH82 WB Chain Link Fence (36 Inch Splash Guard) (Typ)5'-1" Min3" HMA over Waterproofing (Membrane) B21 B24 S. SOWAL A.PRICE Proposed Concrete Pier Cap Proposed Concrete Column (Typ) 177 $$PLOT_INFO$$All seals for this set of drawings are applied to the cover page(s) $$FILES$$ $$DATE$$ Date Comments Init. Sheet Revisions As Constructed No Revisions: Revised: Void:Sheet Subset: Detailer: Designer: Sheet Number 2023-218 Project No./CodeSH82 over Castle Creek Bridge BRIDGE Subset Sheets: of Structure Numbers Print Date: File Name: Horiz. Scale:AS NOTED H-09-B REPLACEMENT - 2 LANE ALTERNATIVE CONSTRUCTION PHASING (1 OF 3) 10 PHASE 2 SECTION AT BRIDGE SCALE: 1/8" = 1'-0" (Looking East) PHASE 1 SECTION AT BRIDGE SCALE: 1/8" = 1'-0" (Looking East) PHASE 1: -Construct new piers under the existing superstructure. -Traffic to remain on existing structure during this phase of construction. PHASE 2: -Install Temporary Barriers (pinned to existing bridge deck). -Demolish southern portion of existing bridge. Remove exterior girder bearing seats from epiers and abutments. -Build new section of bridge at the southern edge. -EB and WB traffic shall remain on the existing bridge. A single lane shall be provided. -Sidewalk shall remain on the existing structure. 8'-0"2'-0"Phase 2 Single Traffic Lane = 11'-0"2'-0" Sidewalk Shldr Shldr Limits of Phase 2 Construction = 18'-6" Temporary Barrier (Pinned) Bridge Rail Type 9 Existing Utilities (to be reset)(Typ) B22 B24 S. SOWAL A.PRICE 8'-0"2'-6"2 Lane @ 11'-0" = 22'-0" Sidewalk Shldr 2'-6" Shldr 5'-0" Sidewalk SH82 WB SH82 EB Existing Superstructure Existing Utilities Newly Constructed Pier Cap and Columns Existing Pier Cap and Column Existing Pier Cap and Column Newly Constructed Superstructure 3"MinTemporary Support 178 $$PLOT_INFO$$All seals for this set of drawings are applied to the cover page(s) $$FILES$$ $$DATE$$ Date Comments Init. Sheet Revisions As Constructed No Revisions: Revised: Void:Sheet Subset: Detailer: Designer: Sheet Number 2023-218 Project No./CodeSH82 over Castle Creek Bridge BRIDGE Subset Sheets: of Structure Numbers Print Date: File Name: Horiz. Scale:AS NOTED H-09-B REPLACEMENT - 2 LANE ALTERNATIVE CONSTRUCTION PHASING (2 OF 3) 11 PHASE 4 SECTION AT BRIDGE SCALE: 1/8" = 1'-0" (Looking East) PHASE 3 SECTION AT BRIDGE SCALE: 1/8" = 1'-0" (Looking East) PHASE 3: PHASE 4: -Install Temporary Barriers (pinned to new deck). -Demolish remaining portion of existing bridge. -Build new section of bridge. -EB and WB traffic shall be moved to newly constructed bridge segments. -Pedestrian access is rerouted to under the bridge, along existing trail. -Install Temporary Barriers (pinned to existing bridge and pinned to newly constructed deck). -Demolish northern portion of existing bridge. Remove exterior girder bearing seats from piers and abutments. -Build new section of bridge at northern edge. -Reset existing utilities in hanger along the northern overhang. -EB and WB traffic shall move to the southern portion of the newly constructed bridge. A single lane shall be provided. -Pedestrian access shall be provided on the remaining portion of the existing bridge. Limits of Phase 3 Construction = 18'-6"5'-9" Pedestrian 2'-0"Phase 3 Single Traffic Lane = 11'-0"2'-0" Temporary Barrier (Pinned) (Typ) Bridge Rail Type 9 (Typ) Reset Existing Utilities (Typ) Temporary Barrier (Pinned) (Typ) ShldrShldr Limits of Phase 4 Construction = 6'-10" 2'-0"1 Lane @ 11'-0" = 11'-0"2'-0" ShldrShldr 2'-0"1 Lane @ 11'-0" = 11'-0"2'-0" ShldrShldr Bridge Rail Type 9 (Typ) Reset Existing Utilities (Typ) SH82 WB SH82 EB Newly Constructed Superstructure Temporary Support Existing Pier Cap and Column Existing Pier Cap and Column Newly Constructed Superstructure B23 B24 S. SOWAL A.PRICE 179 $$PLOT_INFO$$All seals for this set of drawings are applied to the cover page(s) $$FILES$$ $$DATE$$ Date Comments Init. Sheet Revisions As Constructed No Revisions: Revised: Void:Sheet Subset: Detailer: Designer: Sheet Number 2023-218 Project No./CodeSH82 over Castle Creek Bridge BRIDGE Subset Sheets: of Structure Numbers Print Date: File Name: Horiz. Scale:AS NOTED H-09-B REPLACEMENT - 2 LANE ALTERNATIVE CONSTRUCTION PHASING (3 OF 3) 13 FINAL CONFIGURATION SCALE: 1/8" = 1'-0" (Looking East) PHASE 5 SECTION AT BRIDGE SCALE: 1/8" = 1'-0" (Looking East) PHASE 5: -Join new bridge segments with closure pour. FINAL CONFIGURATION: -Remove temporary Barriers. -Construct sidewalk. -Install HMA over Waterproofing (Membrane). -Install Chain Link Fence (36 inch Splash Guard). -Remove existing piers and abutments (all existing substructure) 2'-6" Clousure Pour (Typ) 10'-0" Sidewalk 6'-11"2 Lanes @ 11'-0" = 22'-0"6'-11" Shldr Shldr SH82 WB SH82 EB SH82 WB SH82 EB B24 B24 S. SOWAL A.PRICE 2'-0"1 Lane @ 11'-0" = 11'-0"2'-0" ShldrShldr 2'-0"1 Lane @ 11'-0" = 11'-0"2'-0" ShldrShldr Bridge Rail Type 9 (Typ) Existing Pier Cap and Column Bridge Rail Type 9 (Typ) Chain Link Fence (36 Inch Splash Guard) (Typ) 180 Appendix J Conceptual Three-lane Bridge Replacement Plans 181 677+00 682+00679+00678+00 680+00 681+00 fofofofofofofofofofofofofo fofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofossssssssssssssssx x xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx $$PLOT_INFO$$All seals for this set of drawings are applied to the cover page(s) $$FILES$$ $$DATE$$ Date Comments Init. Sheet Revisions As Constructed No Revisions: Revised: Void:Sheet Subset: Detailer: Designer: Sheet Number 2023-218 Project No./CodeSH82 over Castle Creek Bridge BRIDGE Subset Sheets: of Structure Numbers Print Date: File Name: Horiz. Scale:AS NOTED H-09-B REPLACEMENT - 3 LANE ALTERNATIVE GENERAL LAYOUT 13 ℄ Brg Abut 1 ℄ Pier 2 ℄ Brg Abut 5℄ Pier 3 ℄ Pier 4 420'-0" PLAN SCALE: 1" = 40' ELEVATION SCALE: 1" = 40' 97'-6"97'-6"112'-6"112'-6"CASTLE CREEKExisting Structure H-09-B (to be removed) BF Abut 5 ℄ Brg Abut 1 ℄ Pier 2 ℄ Brg Abut 5 ℄ Pier 3 ℄ Pier 4 420'-0" 97'-6"97'-6"112'-6"112'-6"26'-512"1'-6" Bridge3 Lanes @ 11'-0"= 33'-0"3'-0"1'-6" Bridge90°0'0"(Typ)N74°23'29"W Existing Utilities (to be reset) See Note 2 Proposed Structure BF Abut 1 20'-0" Approach Slab (Typ)ShldrShldrRail Type 9Rail Type 9Sdwlk7910 7900 7890 7880 7870 7860 7850 7840 7830 ℄ SH82 See Note 1 BF Abut 1 Expansion Jt Finished Grade E Power Plant Road Existing Grade See Note 3 Power Plant Road Harbour Lane Sleeper Slab (Typ) Expansion Jt Approach Slab (Typ) BF Abut 5 E NOTES 1.Existing SH82 alignment shown. 2.Existing utility locations are approximate. 3.Existing grade is approximate. SH82 EB to ASPEN FFF 7910 7900 7890 7880 7870 7860 7850 7840 7830 Pedestrian Trail C Power Plant RoadL C Harbour LaneL SH82 WB to GLENWOOD SPRINGS C Power Plant RoadL52'-0"Out to Out25'-612"10'-0"3'-0"Existing Structure H-09-B (to be removed) Castle Creek B30 B34 S. SOWAL A.PRICE 182 $$PLOT_INFO$$All seals for this set of drawings are applied to the cover page(s) $$FILES$$ $$DATE$$ Date Comments Init. Sheet Revisions As Constructed No Revisions: Revised: Void:Sheet Subset: Detailer: Designer: Sheet Number 2023-218 Project No./CodeSH82 over Castle Creek Bridge BRIDGE Subset Sheets: of Structure Numbers Print Date: File Name: Horiz. Scale:AS NOTED H-09-B REPLACEMENT - 3 LANE ALTERNATIVE TYPICAL SECTION 15 TYPICAL SECTION SCALE: 1/4" = 1'-0" (Looking East, at Pier) 52'-0" Out to Out 3'-0" Shldr 3 Lanes @ 11'-0" = 33'-0"3'-0" Shldr 10'-0" Sidewalk 25'-612"26'-512" 1'-6" Bridge Rail 1'-6" Bridge Rail ℄ SH82 Type 9 Type 9 2 - 2"Ø Electrical Conduit for Future use (Typ) Reset Existing Utilities Post-Tensioned Cast-in-Place Concrete Box Girder Structural Concrete Stain (Typ) 2.00%2.00% SH82 EBSH82 WB Chain Link Fence (36 Inch Splash Guard) (Typ) 3" HMA over Waterproofing (Membrane) SH82 GP Proposed Concrete Column (Typ) B31 B34 S. SOWAL A.PRICE 183 $$PLOT_INFO$$All seals for this set of drawings are applied to the cover page(s) $$FILES$$ $$DATE$$ Date Comments Init. Sheet Revisions As Constructed No Revisions: Revised: Void:Sheet Subset: Detailer: Designer: Sheet Number 2023-218 Project No./CodeSH82 over Castle Creek Bridge BRIDGE Subset Sheets: of Structure Numbers Print Date: File Name: Horiz. Scale:AS NOTED H-09-B REPLACEMENT - 3 LANE ALTERNATIVE CONSTRUCTION PHASING (1 OF 3) 15 PHASE 2 SECTION AT BRIDGE SCALE: 1/8" = 1'-0" (Looking East) PHASE 1 SECTION AT BRIDGE SCALE: 1/8" = 1'-0" (Looking East) PHASE 1: -Construct new piers under the existing superstructure. -Traffic to remain on existing structure during this phase of construction. PHASE 2: -Install Temporary Barriers (pinned to existing bridge deck). -Demolish southern portion of existing bridge. Remove exterior girder bearing seats from piers and abutments. -Build new section of bridge at the southern edge. -EB and WB traffic shall remain on the existing bridge. A single lane shall be provided. -Sidewalk shall remain on the existing structure. 8'-0"2'-0"Phase 2 Single Traffic Lane = 11'-0"2'-0" Sidewalk Shldr Shldr Limits of Phase 2 Construction = 20'-6" Temporary Barrier (Pinned) Bridge Rail Type 9 Existing Utilities (to be reset)(Typ) 8'-0"2'-6"2 Lane @ 11'-0" = 22'-0" Sidewalk Shldr 2'-6" Shldr 5'-0" Sidewalk SH82 WB SH82 EB Existing Superstructure Existing Utilities Newly Constructed Pier Cap and Columns Existing Pier Cap and Column Existing Pier Cap and Column Newly Constructed Superstructure 3"MinTemporary Support B32 B34 S. SOWAL A.PRICE 184 $$PLOT_INFO$$All seals for this set of drawings are applied to the cover page(s) $$FILES$$ $$DATE$$ Date Comments Init. Sheet Revisions As Constructed No Revisions: Revised: Void:Sheet Subset: Detailer: Designer: Sheet Number 2023-218 Project No./CodeSH82 over Castle Creek Bridge BRIDGE Subset Sheets: of Structure Numbers Print Date: File Name: Horiz. Scale:AS NOTED H-09-B REPLACEMENT - 3 LANE ALTERNATIVE CONSTRUCTION PHASING (2 OF 3) 16 PHASE 4 SECTION AT BRIDGE SCALE: 1/8" = 1'-0" (Looking East) PHASE 3 SECTION AT BRIDGE SCALE: 1/8" = 1'-0" (Looking East) PHASE 3: PHASE 4: -Install Temporary Barriers (pinned to new deck). -Demolish remaining portion of existing bridge. -Build new section of bridge. -EB and WB traffic shall be moved to newly constructed bridge segments. -Pedestrian access is rerouted to under the bridge, along existing trail. -Install Temporary Barriers (pinned to existing bridge and pinned to newly constructed deck). -Demolish northern portion of existing bridge. Remove exterior girder bearing seats from piers and abutments. -Build new section of bridge at northern edge. -Reset existing utilities in hanger along the northern overhang. -EB and WB traffic shall move to the southern portion of the newly constructed bridge. A single lane shall be provided. -Pedestrian access shall be provided on the remaining portion of the existing bridge. Limits of Phase 3 Construction = 19'-8"5'-9" Pedestrian 3'-0"Phase 3 Single Traffic Lane = 11'-0"3'-0" Temporary Barrier (Pinned) (Typ) Bridge Rail Type 9 (Typ) Reset Existing Utilities (Typ) Temporary Barrier (Pinned) (Typ) ShldrShldr Limits of Phase 4 Construction = 6'-10" 3'-0"1 Lane @ 11'-0" = 11'-0"3'-0" ShldrShldr 2'-7"1 Lane @ 11'-0" = 11'-0"2'-7" ShldrShldr Bridge Rail Type 9 Reset Existing Utilities (Typ) SH82 WB SH82 EB B33 B34 S. SOWAL A.PRICE Newly Constructed Pier Cap and Columns Existing Pier Cap and Column Temporary Support Newly Constructed Superstructure Existing Pier Cap and Column 185 $$PLOT_INFO$$All seals for this set of drawings are applied to the cover page(s) $$FILES$$ $$DATE$$ Date Comments Init. Sheet Revisions As Constructed No Revisions: Revised: Void:Sheet Subset: Detailer: Designer: Sheet Number 2023-218 Project No./CodeSH82 over Castle Creek Bridge BRIDGE Subset Sheets: of Structure Numbers Print Date: File Name: Horiz. Scale:AS NOTED H-09-B REPLACEMENT - 3 LANE ALTERNATIVE CONSTRUCTION PHASING (3 OF 3) 18 FINAL CONFIGURATION SCALE: 1/8" = 1'-0" (Looking East) PHASE 5 SECTION AT BRIDGE SCALE: 1/8" = 1'-0" (Looking East) PHASE 5: -Join new bridge segments with closure pour. FINAL CONFIGURATION: -Remove temporary Barriers. -Construct sidewalk. -Install HMA over Waterproofing (Membrane). -Install Chain Link Fence (36 inch Splash Guard). -Remove existing piers and abutments (all existing substructure). 10'-0" Sidewalk 3'-0"3 Lanes @ 11'-0" = 33'-0"3'-0" Shldr Shldr SH82 WB SH82 EB SH82 WB SH82 EB 2'-6" Clousure Pour (Typ) SH82 GP 3'-0"1 Lane @ 11'-0" = 11'-0"3'-0" ShldrShldr 2'-7"1 Lane @ 11'-0" = 11'-0"2'-7" ShldrShldr Bridge Rail Type 9 (Typ) Existing Pier Cap and Column Bridge Rail Type 9 (Typ) Chain Link Fence (36 Inch Splash Guard) (Typ) B34 B34 S. SOWAL A.PRICE 186 Appendix K Overall Project Cost Matrix – Bridge Rehabilitation and Replacement Options 187 Jacobs Engineering Castle Creek Bridge Overall Project Costs Rehabilitation and Replacement CIP Concrete Steel CIP Concrete Steel CIP Concrete Steel CIP Concrete Steel (A) Bridge Construction Items 5,900,000$ 9,500,000$ 10,000,000$ 10,000,000$ 10,500,000$ 11,100,000$ 11,700,000$ 10,000,000$ 10,500,000$ Unlisted Construction Items Mobilization (15%)885,000$ 1,425,000$ 1,500,000$ 1,500,000$ 1,575,000$ 1,665,000$ 1,755,000$ 1,500,000$ 1,575,000$ Removal of Existing CC Bridge -$ 4,000,000$ 4,000,000$ 4,000,000$ 4,000,000$ 4,000,000$ 4,000,000$ 4,000,000$ 4,000,000$ Utilities (relocation of City fiber)15,000$ 15,000$ 15,000$ 15,000$ 15,000$ 15,000$ 15,000$ 15,000$ 15,000$ Roadway Approaches/Improvements 500,000$ 2,000,000$ 2,000,000$ 3,500,000$ 3,500,000$ 3,500,000$ 3,500,000$ 4,500,000$ 4,500,000$ Temporary Detour Construction (across Marolt-Thomas) 13,000,000$ 13,000,000$ 13,000,000$ 13,000,000$ 13,000,000$ 13,000,000$ 13,000,000$ -$ -$ Traffic Control & Transit/Bus Priority 3,650,000$ 7,300,000$ 7,300,000$ 7,300,000$ 7,300,000$ 5,475,000$ 5,475,000$ 7,300,000$ 7,300,000$ Subtotal Unlisted Construction Items 18,050,000$ 27,740,000$ 27,815,000$ 29,315,000$ 29,390,000$ 27,655,000$ 27,745,000$ 17,315,000$ 17,390,000$ Other Contingency Items (20%) 3,610,000$ 5,548,000$ 5,563,000$ 5,863,000$ 5,878,000$ 5,531,000$ 5,549,000$ 3,463,000$ 3,478,000$ (B) Total Unlisted Construction Items 21,660,000$ 33,288,000$ 33,378,000$ 35,178,000$ 35,268,000$ 33,186,000$ 33,294,000$ 20,778,000$ 20,868,000$ (C) Total of Construction Items Cost (A + B) 27,560,000$ 42,788,000$ 43,378,000$ 45,178,000$ 45,768,000$ 44,286,000$ 44,994,000$ 30,778,000$ 31,368,000$ (D) NEPA 750,000$ 2,000,000$ 2,000,000$ 3,000,000$ 3,000,000$ 3,000,000$ 3,000,000$ 3,000,000$ 3,000,000$ (E) Engineering Design - Rehab 10%/Replace 15% of (C) 2,756,000$ 6,418,200$ 6,506,700$ 6,776,700$ 6,865,200$ 6,642,900$ 6,749,100$ 4,616,700$ 4,705,200$ (F) ROW and TCEs 4,500,000$ 4,500,000$ 4,500,000$ 4,500,000$ 4,500,000$ 15,092,000$ 15,092,000$ 21,134,000$ 21,134,000$ (G) Public Involvement During Construction 876,000$ 1,752,000$ 1,752,000$ 1,752,000$ 1,752,000$ 1,314,000$ 1,314,000$ 1,752,000$ 1,752,000$ (H) CE&I - 26% of (C)7,165,600$ 11,124,880$ 11,278,280$ 11,746,280$ 11,899,680$ 11,514,360$ 11,698,440$ 8,002,280$ 8,155,680$ (I) Overall Project Cost (2024)(C+D+E+F+G+H) 43,607,600$ 68,583,080$ 69,414,980$ 72,952,980$ 73,784,880$ 81,849,260$ 82,847,540$ 69,282,980$ 70,114,880$ Overall Project Cost Inflated to 2028, (I) - inflated 4% yoy 51,014,724$ 80,232,503$ 81,205,709$ 85,344,668$ 86,317,873$ 95,752,057$ 96,919,904$ 81,051,287$ 82,024,493$ Bridge Rehabilitation (functionally obsolete) Three-Lane Bridge Centered Fastest Shifted Replace Two-Lane Bridge 188 Jacobs Engineering Castle Creek Bridge Overall Project Costs Rehabilitation and Replacement Assumptions:Options: 1) Utility Relocations Rehabilitation - Rehabilitate the existing bridge in-place - reamains Functionally Obsoltete Removal & replacement of existing conduits are included in bridge construction cost. 2-Lane Replace - Replace the existing bridge in kind (CIP Concrete or Steel) Relocation of City fiber (~700 lf) included in unlisted items.3-Lane Centered - Replace the existing bridge with 3-Lanes centered on exsiting bridge (CIP Concrete or Steel) Relocation of Comcast, Lumen/Ting fiber lines will be responsibility of utility owner - not included in project cost.3-Lane Faster - Replace the existing bridge with 3-Lanes slightly shifted but faster construction timeframe (CIP Concrete or Steel) 3-Lane Shifted - Replace the existing bridge with 3-Lanes shifted south to facilitate 2-way traffic during construction (CIP Concrete or Steel) 2) ROW & TCEs (Right-of-Way and Temp. Construction Easements) ROW is estimated at $8,000/SF. 3-Lane Faster = 574 SF (bridge approach) 4,592,000$ 3-Lane Shifted = 673 SF (bridge approach) 5,384,000$ TCE costs are estimated at $1,500/SF. Rehabilitation - assume TCE 10' south side of bridge 300 LF 4,500,000$ Bridge Reconstruction - assumes TCE on 2 properties 2-Lane Replace - (10' South side of bridge 300 LF)4,500,000$ 3-Lane Centered - (10' South side of bridge 300 LF)4,500,000$ 3-Lane Faster - (20' South side of bridge 350 LF)10,500,000$ 3-Lane Shifted* - (30' South side of bridge 350 LF)15,750,000$ *Does not include ROW costs for 3-Lane roadway realignment Inbound Detour assumes it is in Main St. easement east of Castle Creek 3) Detour Options & Traffic Control (TC) Outbound CCB lane w/Inbound detour across the Marolt-Thomas - $13 million Traffic Control and Transit Priority estimated at $5K/day 3-Lane Shifted bridge replacement does not need a detour Traffic Control estimated at $5K per Day - includes establishing a priority for buses 4) Construction Duration Bridge Rehabilitation ~ 2-years 2-Lane Replace ~ 4-years 3-Lane Centered ~ 4-years 3-Lane Faster ~ 3-years 3-Lane Shifted ~ 4-years Public Involvment estimated at $1,200/day for construction duration. 5) CE&I (Construction Engineering & Indirects) Current value for CDOT construction projects is 26% 189 1. Introduction This memorandum summarizes a concept analysis and safety evaluation performed by Jacobs Engineering Group, Inc. (Jacobs) regarding the S-curve alignment along State Highway 82 (SH82) in Aspen, Colorado. The City of Aspen (City) has requested Jacobs investigate design options and impacts of increasing the curve radii (curve softening) at two 90-degree (S-curve) turn locations entering the City. Figure 1. S-curve Alignment Study Area Subject DRAFT SH 82 S-curve Technical Memo Project Name Entrance to Aspen/Castle Creek Bridge Attention City of Aspen From Jacobs Engineering Date February 2024 Copies to Project File Memorandum 190 2. History and Crash Data As a resort town and year-round destination for many travelers, traffic and congestion has continued to grow and challenge the existing infrastructure. Since the Entrance to Aspen Final Environmental Impact Statement (CDOT, 1997) and Record of Decision (ROD) (FHWA, 1998), many transportation and traffic studies have occurred over the years to evaluate SH82 improvements through the City. Exhibit A presents the transportation studies and implemented improvements specific to addressing issues on the S-curves and Castle Creek Bridge over the last 20 years. Not all studies were conclusive, resulting in non- implemented improvements. The safety and driver expectations of commuters in Aspen and along SH82 is a key consideration when evaluating corridor modifications. According to the latest 5-year crash data (2018 to 2022), the majority of incidents were rear-end collisions occurring at the Castle Creek Bridge, on North 6th Street, and near or between the S-curve locations. Rear-end collisions are a symptom of congestion and speed differentials between vehicles. Figure 2. Yearly Collision Count – SH82 As shown on Figure 2, crashes dipped during the COVID-19 pandemic; however, post-COVID-19, crash statistics drastically increased and began to highlight an upward trend from 2018 (ignoring COVID-19 data). 0 5 10 15 20 25 2018 2019 2020 2021 2022 SH82 - Yearly Collision Count Disregarding COVID years, crash data trending upward. 191 Several locations that experience higher numbers of crashes, shown on Figure 4, have pinch points that contribute to these crashes. To address some of these crash problems and types (Figure 3), mitigation options could include minimizing conflict points by extending designated transit lanes, removing access at select intersecting streets, and reconfiguring the outbound zipper lane on West Main Street. The options discussed in the following section feature these enhancements to reduce conflict points while improving traffic flow. Figure 3. Collision Classification – SH82 (2018 to 2022) Figure 4. Collision Location – SH82 (2018 to 2022) 3. Options Developed Two options were developed to smooth the S-curves while improving safety and outbound traffic flow, prioritizing buses, and maintaining bicycle and pedestrian connections. Traffic flow was not modeled, but access points were selectively eliminated to reduce conflict points and ease traffic congestion. Further traffic impact analysis (that is, traffic modeling) would be required to make quantitative assessments (such as travel time or speeds) regarding the options’ travel benefits. The options were laid out to qualitatively assess the impacts of softening the curves, widening the corridor to four lanes, and eliminating access. Softening the curves was strategic because layouts were based on accommodating buses in the outside lanes, heavy trucks (WB-67 design vehicle), and a future fixed rail transit system. For the transit system, an assumption of a light rail transit (LRT) vehicle was selected to set a minimum radius for the curves (refer to Section 6. Transit Options). To accommodate the larger vehicles through the curves, lane width widening is needed in the S-curve corners. Each option includes bike and pedestrian accommodations to help safely facilitate connectivity and pedestrian travel throughout the corridor. As alignment changes may impact pedestrian facilities, sidewalk modifications and connections are proposed to propagate hike and bike travel from Castle Creek Bridge to North 6th St. 15% 13% 19% 18% 4% 16% 7% 1%6% SH82 - Collision Location Castle Creek Bridge N 5th St N 6th St N 7th St S 7th St N 8th St W Hallam St Bleeker St W Main St 4% 6% 10% 19% 40% 15% 6% SH82 - Collision Classification Approach Turn Pedestrian/Bicycle Broadside Fixed Object Rear-End Sideswipe Unknown 192 Option 1 is designed to work with the existing two-lane bridge, while Option 2 is designed to match a three-lane bridge over Castle Creek. 1 Option 2 would extend the outbound bus lane to Cemetery Lane, where a bus queue jump could be designed to prioritize transit. Table 1 lists and compares critical design elements of Option 1 and Option 2. Drawings depicting each option are provided in Exhibit B. These proposed improvements would have impacts, including right-of-way (ROW) and temporary construction easement (TCE) acquisition, removal of existing trees, and minor impacts to a historic property. The design options and associated impacts are noted in Table 1 for each option. Table 1. Options 1 and 2: Design Elements and Impacts Design Elements and Impacts Option 1 Option 2 Two lanes of travel in each direction. Outer lanes designated bus/transit lanes Matches three-lane bridge section. Outer outbound lane designated bus/transit lane Matches two-lane bridge section Ingress/Egress to North 8th Street. removed Ingress/Egress to North 7th Street removed Access from outbound SH82 to North 7th Street Increase radii at S-curves (accommodates large vehicles and future transit system) Ingress/Egress to South 7th Street and West Main Street removed ROW/TCE acquisition (square feet) 2,000/1,800 2,200/5,000 Mature trees impacted by option 7 15 Historic property impacts (Not Adverse) – 7th/Main Street Queue jump at Cemetery Lane to facilitate merge of outbound buses with general traffic Main Street zipper lane removed and converted to merge lane Better facilitates outbound flow of traffic 1 As part of a separate task, Jacobs is evaluating rehabilitating or replacing the existing SH82/Castle Creek Bridge to accommodate two or three lanes. 193 The Christian Science Society building at 734 West Main Street is the one historic property that is impacted by both options. Two large, 36-inch diameter trees are removed for each option. Right-of- way and temporary construction easements are needed for softening the curve (encroachment on the property) and reconstructing the sidewalk on this property. Even with these impacts the affect is expected to be non-adverse for this historic property. Figures 5 and 6 provide examples of impacted trees with both options. Figures 5 and 6. Mature Trees Impacted by Both Options Some design elements from one option can be picked and implemented (à la carte) on the other option as desired. For instance, Option 2 features removing ingress and egress to South 7th Street; this could be done on Option 1 as well. 4. Operational Benefits The following sections summarize qualitative assessments of operations based on engineering judgment. 4.1 Designated Bus Lanes A critical design element in the proposed options is the extension of designated bus lanes through the S- curves. It is generally understood incorporating designated bus lanes will help alleviate congestion and improve safety by removing zippering of bus and general traffic on SH82. Currently, existing outbound buses merge with general traffic near North 6th Street and Main Street. The reintroduction of bus traffic to general traffic creates a bottleneck, causing friction between buses and general traffic. Therefore, both options considered repositioning or removing this merge. In Option 1, the outbound bus lane is extended to the bus stop near 8th Street on SH82. Option 2 would carry the outbound bus over a widened three-lane bridge and feature a queue jump for the transit lane at the Cemetery Lane signal, improving safety, reducing congestion, and prioritizing transit. Additionally, signal timing optimization at Cemetery Lane can be evaluated to improve traffic operations for all traffic. 194 4.2 S-curve Accesses To help with evening peak period traffic flow, the City commissioned a project that removed access to SH82 from West Hallam Street. Additionally, the City manually suspends access to SH82 from North 7th Street during evening peak hours by placing a barricade to keep west end traffic from entering SH82. Removing access points along SH82 will improve traffic flow and reduce conflict points and potentially traffic collisions. Option 1 and Option 2 each propose eliminating ingress/egress at the 8th Street access to SH82. Option 1 also eliminates access at Curve-1 (North 7th Street) by wrapping West Hallam Street into North 7th Street (Figure 7). Option 2 proposes maintaining egress from SH82 to North 7th Street at Curve-1. Pedestrian connectivity and safety are critical elements of each option. Sidewalks and crosswalks are planned for each option, and the existing inbound and outbound bus stops will remain in both options. Figure 7. Curve-1 Option 1 Figure 8. Curve-1 Option 2 Option 1 proposes a raised median at Curve-1, which splits opposing traffic on the curve but is not intended to be used as a pedestrian refuge (Figure 7). Option 2 proposes a painted median at Curve-1, providing a smaller separation of opposing traffic (Figure 8). Option 2 could be designed with a raised median similar to Option 1. At Curve-2, Option 1 provides the current daily movements for users to continue onto West Main Street to access the Aspen Villas or make a left onto South 7th Street. Because of the curve softening at this location, the stop bar for the left turn is set back about 40 feet from its current position, providing longer time needed to cross the road with oncoming traffic (Figure 9). Option 2 proposes to eliminate ingress/egress access to SH82 at Curve-2, cutting access from South 7th Street and West Main Street by connecting them (Figure 10). Eliminating access at this curve will reduce vehicle conflicts on SH82 and improve traffic flow through the curve. 195 Figure 9. Curve-2 Option 1 Figure 10. Curve-2 Option 2 4.3 Widening at Castle Creek Bridge Approaches to narrow bridges tend to slow and congest traffic because the traveler feels compressed by both oncoming traffic and the bridge elements along the driving lane. Creating additional capacity and shoulder widths by widening the bridge at Castle Creek would improve safety and facilitate traffic flow. Increasing capacity at the bridge is also critical when considering emergency egress. Per the City’s evacuation models, it will take more than 12 hours to completely evacuate the City, even using both lanes of the existing bridge for outbound. Considering all S-curve improvements, the existing two-lane bridge will remain a bottleneck and result in significant congestion during an evacuation event and daily peak periods. Construction of a widened three-lane Castle Creek Bridge would be beneficial for traffic flow, safety, and emergency evacuation; however, the widening option has numerous challenges and impacts. Details are captured in the SH82 Castle Creek Bridge Feasibility Study (Jacobs 2024). 5. SH82 Pinch Point Analysis Pinch points can be defined as a place where a road or path becomes narrow or a place where there is often a lot of traffic convergence, causing the traffic to slow down or stop. SH82 has several pinch points that inhibit the flow of traffic, resulting in congestion or increase accident potential. S-curve modifications may alleviate some conflict points; however, congestion and queueing will remain if the pinch points are not properly addressed. The West End Neighborhood Traffic Study SH82 (Fox Tuttle, 2022) peak hour volume data indicates the S-curves, the Maroon Creek roundabout, and other traffic constrictions (pinch points) reduce capacity on SH82 in the Castle Creek Bridge area to between 1,000 to 1,400 vehicles per hour. Figure 11 presents pinch point locations along the corridor. The six pinch points are as follows: 1. Maroon Creek Roundabout 2. Existing Castle Creek Bridge 3. 90-degree S-curve (7th/Hallam Street)—(Curve-1) 4. 90-degree S-curve (7th/Main Street)—(Curve-2) 5. Outbound Bus Merge 196 6. Zipper Lane Both options soften the S-curves and remove access at conflicting streets, providing substantive improvements to pinch points 3 and 4. Additionally, pinch point 5 will be relocated but not resolved because buses will have to merge with general traffic at some other westerly point (depending on the option). Pinch point 6 is also being addressed to serve as an outside merge for outbound traffic rather than an atypical inside zipper lane, which will be a safer merge but will still cause traffic friction and congestion. Figure 11. SH82 Pinch Point Exhibit (See attached Exhibit D for enlarged view) Although each option proposes improvements for the pinch points described, these are not solutions that solve the bottleneck issues entirely. The Maroon Creek roundabout remains in each scenario, and Castle Creek Bridge will remain a point of restriction as a narrow two-lane bridge for Option 1. 6. Transit Options One of the considerations in adding designated bus lanes and softening the curves along the route now is that these bus lanes can be repurposed later for future transit options. Advancements in transit technology could provide more options than when the Entrance to Aspen ROD (FHWA, 1998) was completed. These advancements include improvements to vehicle, route, and station designs with an emphasis on efficiency and performance and an eye toward sustainability and reducing greenhouse gas emissions. Transit technology options include LRT, trolleybus, battery electric and fuel cell electric buses, and hybrid in-motion charging trolley buses. Technology selection will naturally be influenced by the subject corridor, including considerations of capacity, trip frequency, and snow. Given the common inclement weather in the project corridor, issues such as snow removal and maintenance of facilities, management 197 of mixed traffic, and other issues can all be assessed through a technology comparison. Track systems and overhead lines can be adversely affected by snow and ice, and even high winds can disrupt the bus/electric line connections. The proposed curve softening improvements will accommodate a variety of transit options and will not preclude a future fixed rail LRT system when ridership and funding can support such an investment. There are numerous options regarding bus technology, with each providing its own pros and cons as it relates to performance, infrastructure impacts, and operational and maintenance costs. If ridership warrants the consideration of longer articulated buses, these buses have a better turning radii than a typical bus, so the proposed improvements would be more than adequate to support these longer buses as well. Exhibit E documents some transit options for the corridor. 7. Impact Costs of Options Table 2 presents estimated costs of impacts from the curve softening based on engineering judgment. Impact costs would likely change if options advance and are refined for the better or worse. Each proposed option will result in property impacts, necessary for ROW acquisition, TCEs, and tree removals. ROW acquisition costs are based on recent acquisition data from City staff. Quantity Unit Approx. Unit Cost Estimated Cost Opt 1 Opt 2 Opt 1 Opt 2 ROW Acquisition 2,000 2,200 Square foot $ 8,000 $ 16,000,000 $ 17,600,000 Temporary Construction Easement 1,800 5,000 Square foot $ 1,500 $ 2,700,000 $ 7,500,000 Tree Removals 7 15 Each $ 10,000 $ 70,000 $ 150,000 Impact Costs $18,770,000 $25,250,000 Table 2. SH82 Option Impact Cost Comparison 8. Conclusions The two options discussed in this memorandum may improve traffic mobility and safety within the S- curves but would not address larger congestion and travel time problems. Implementation of these options would not adequately address the other nearby corridor pinch points and do not improve emergency egress out of Aspen. Overall project costs for design, construction and impact costs are quite high for these improvements. Considering Option 1 is less impactful and able to implement with the existing bridge, construction and design is estimated at $4M. When including ROW acquisition and TCE (impact costs), the total cost is approximated to be nearly $23M. Though these estimates provide 198 perspective of estimated cost and impacts against benefits to safety and mobility, further detailed design and construction cost estimates are needed to assess total cost more adequately for each option. 199 Exhibit A – History of studies and implemented improvements relative to S-Curves 200 201 S Curve and CCB Improvements for trac flow and pedestrian safety (2002-2024)City of Aspen N 8TH STN 7TH STN 6TH STW HALL A M S T W MAIN S TCEMETERY LNW BLEE K E R S T Source: Esri Community Maps Contributors, City of Aspen GIS, Pitkin County, © OpenStreetMap, Microsoft, Esri, TomTom, Garmin, SafeGraph, GeoTechnologies, Inc, METI/NASA, USGS, Bureau of Land Management, EPA, NPS, US Census Bureau, USDA, USFWS | Maxar, Microsoft Traffic flow: Improved intersection configuration. Traffic flow: Island modifications made Traffic flow: Turn restrictions implemented Pedestrian Safety: Crosswalk implemented. Pedestrian Safety: Bridge sidewalk widened from 5' to 8'. Concrete and steel barrier added.Transit Capacity: Main Street PM Peak transit lane added Legend Castle Creek Bridge Connectivity Study S Curves Citizen Task Force Study Traffic flow: Access closures implemented. 202 Exhibit B – S-Curves Option 1 203 Option 1 | Sheet 1City of Aspen 0'30'60'120' LEGEND Trees Impacted Access to SH 82 RemovedACCESS REMOVED Dedicated Bus Lane Sidewalk General Traffic Lane Remove Zipper Lane Raised Median Historical Property Impacted 12'12' GENERAL TRAFFIC SECTION A-A GENERAL TRAFFIC SH 82 12'12'12'12'12' SECTION B-B GENERAL TRAFFICDEDICATEDBUS LANE GENERAL TRAFFIC DEDICATEDBUS LANE SH 82 12' –16'12'12'12' –16'VARIES RAISED MEDIAN W BLEEKER STN 8TH STN 7TH STMATCHLINE SHEET 2 W HALLAM ST B B ACCESS REMOVEDA A ACCESS REMOVED SH 82 204 Option 1 | Sheet 2City of Aspen 0'30'60'120' LEGEND Trees Impacted Access to SH 82 RemovedACCESS REMOVED Dedicated Bus Lane Sidewalk General Traffic Lane Remove Zipper Lane Historical Property Impacted Dedicated Bus Lane General Traffic Lane SECTION C-C SH 82 12'12'12'12' SECTION D-D SH 82 12'12'12'12'12' GENERAL TRAFFICDEDICATEDBUS LANE DEDICATEDBUS LANEGENERAL TRAFFIC N 6TH STS 7TH STW MAIN ST MATCHLINE SHEET 1 D D C C SH 82 GENERAL TRAFFIC GENERAL TRAFFICDEDICATEDBUS LANE LEFT TURN ONLY DEDICATEDBUS LANE 205 Exhibit C – S-Curves Option 2 206 Option 2 | Sheet 1City of Aspen 0'30'60'120' LEGEND Trees Impacted Access to SH 82 RemovedACCESS REMOVED Dedicated Bus Lane Sidewalk General Traffic Lane Remove Zipper Lane Historical Property Impacted 12'12'12'12'12'12'12'12'12'12' SECTION B-B GENERAL TRAFFICDEDICATEDBUS LANE GENERAL TRAFFIC DEDICATEDBUS LANE SH 82 12'12'VARIES RAISED MEDIAN 12' –16'12' –16'12'12'12' SH 82 GENERAL TRAFFIC SECTION A-A DEDICATEDBUS LANE GENERAL TRAFFIC W BLEEKER STN 8TH STN 7TH STMATCHLINE SHEET 2 ACCESS REMOVED SH 82 A A B B 207 Option 2 | Sheet 2City of Aspen 0'30'60'120' LEGEND Trees Impacted Access to SH 82 RemovedACCESS REMOVED Dedicated Bus Lane Sidewalk General Traffic Lane Remove Zipper Lane Historical Property Impacted SECTION D-D SH 82 12'12'12'12'12' SECTION C-C SH 82 12'12'12'12' GENERAL TRAFFICDEDICATEDBUS LANE DEDICATEDBUS LANEGENERAL TRAFFIC N 6TH STS 7TH STW MAIN ST ACCESS REMOVED MATCHLINE SHEET 1 D D C C GENERAL TRAFFICDEDICATEDBUS LANE DEDICATEDBUS LANEGENERAL TRAFFIC GENERAL TRAFFIC GENERAL TRAFFICDEDICATEDBUS LANE LEFT TURN ONLY DEDICATEDBUS LANE 208 Exhibit D – Pinch Point Diagram 209 SH 82 Pinch Point ExhibitCity of AspenEnd S-Curve Alternative AnalysisPINCH4PINCH2PINCH1PINCH6PINCH5HPINCH3PINCH 6:Zipper lane merges from 2 lanes to 1 for outbound travellers.MAROON CREEK RDMAROON CRK RDPINCH 5:Designated peak period bus lane ends. Busses merge with local traffic (single lane).Start S-Curve Alternative AnalysisPINCH 3 & 4:90-degree S-Curves with intersecting streets impedes traffic flow and introduces conflict points.PINCH 2:Narrow, 2-lane bridge, constricts the flow of traffic, reducing traveler speed, resulting in queuing and rear-end collisions.PINCH 1: Maroon Creek Roundabout perpetuates movement of traffic, but high traffic volume constricts flow and results in congestion.W MAIN STW BLEEKER STN 6TH STN 7TH STN 5TH STW HALLAM STCEMETERY LNN 8TH STSource: Esri Community Maps Contributors, City of Aspen GIS, Pitkin County, © OpenStreetMap, Microsoft, Esri, TomTom, Garmin, SafeGraph, GeoTechnologies, Inc, METI/NASA, USGS, Bureau of Land Management, EPA, NPS, US Census Bureau, USDA, USFWS | Maxar, Microsoft210 Exhibit E – Transit Options 211 Public Transit Options Aspen, CO 212 ©Jacobs 2024 Light Rail Reduces air pollution and greenhouse gas emissions by providing alternative to private vehicles Higher passenger capacity per lane per hour Lower operating cost per passenger Can be accommodated through S-Curve alignment High construction costs No intermingling of transit and general traffic Overhead electric can be affected by high winds and snow 213 ©Jacobs 2024 Trolleybus 3 Draws power from overhead wires and requires poles Differs from a traditional trolley system in that two wires and two poles are necessary to complete the electrical circuit Bus has greater flexibility to maneuver along the roadway Trackless design that provides more opportunities to mix traffic and maximize use of ROW Track systems and overhead lines can be adversely affected by snow and ice High winds can disrupt the bus/electric line connection 214 ©Jacobs 2024 Battery Electric Bus 4 Battery electric buses and fuel cell electric buses eliminate the need and impacts from electrification lines Accommodates sensitive built environments and constrained ROW Battery life and recharge time can pose a challenge Recharged, stationary, in 5–20-minute sessions 215 ©Jacobs 2024 Overhead In-Motion Charging Trolleybus 5 In-motion charging allows operations to continue smoothly without interruption In-motion charging trolleybuses use overhead catenary wires, covering about 20-40% of the route, otherwise battery powered Reduces overall impacts caused by catenary wires Reduces challenges associated with recharging systems Ideal in rural/urban corridors 216 ©Jacobs 2024 Trackless Tram 6 A hybrid technology utilizing rubber wheels and powered by rechargeable batteries Sustainable public transit with net zero emission vehicle Guided by digital rail with sensors in road, no catenary wires required Optical guidance may not be ideal in heavy snow conditions Vehicle weight requires substantial roadway surfaces 217 1 1. Introduction The purpose of this memorandum is to present options available to the City of Aspen to complete National Environmental Policy Act 1 (NEPA) requirements for replacement of the existing Castle Creek Bridge (CCB) and other improvements associated with the larger Entrance to Aspen (ETA) project. The Entrance to Aspen Final Environmental Impact Statement (FEIS) and Record of Decision (ROD), which includes transportation improvements along State Highway (SH) 82 from Buttermilk to Rubey Park in downtown Aspen, was approved by FHWA in 1998. The Preferred Alternative (PA) that was identified in the 1998 ROD calls for rerouting SH 82 to connect to Main Street, which would be extended to the west and require construction of a new Castle Creek bridge. The PA is described in Section 2.1.2 of this document. Since the ROD was issued, several elements of the PA have been implemented as shown in Figure 1. The portion of the PA involving rerouting SH 82 and reconstructing a new bridge over Castle Creek remains to be completed. The existing Castle Creek bridge, constructed in 1961, is now approaching the end of its service life. When the bridge condition is rated poor through CDOT inspections, it will enter the Statewide Bridge and Tunnel Enterprise eligibility pool for funding and replacement. At that time, CDOT has indicated it would replace the bridge as directed in the PA, unless an alternate NEPA decision is made prior to the need for bridge replacement. As discussed in Section 2.3.2, some city council members have expressed concern about the impacts associated with this final phase. In Summer 2023, the city hired Jacobs Engineering Group, Inc. (Jacobs) to assess options to rehabilitate or replace the existing Castle Creek Bridge, soften the S Curves through town, and evaluate NEPA implications of these and other alternate solutions to the PA. The following courses of action related to the Castle Creek Bridge potentially are available to the City: 1. implement the PA identified in 1998 fully or in phases, 2. implement the PA identified in the 1998 ROD with minor changes, 3. study and implement alternatives that were considered previously in the 1997 FEIS and were either fully evaluated but not selected as the PA (Section Error! Reference source not found.) or dismissed during the alternatives screening process, or 4. study one or more new alternatives. 1 *The National Environmental Policy Act (NEPA) of 1969 established a policy and framework for environmental planning and decision making by Federal agencies. More information can be found on FHWA’s website. Subject Castle Creek Bridge NEPA Process Options Project Name Castle Creek Bridge Attention City of Aspen From Jacobs Date April 2024 Copies to Project File Memorandum Because SH 82 is a state highway managed by CDOT and federal funds have been used to study and build Entrance to Aspen improvements, NEPA and other federal regulations will continue to apply to decision- making regarding improvements at the Castle Creek Bridge. 218 2 This document presents NEPA considerations and requirements for each option including assumptions related to cost, schedule, and risks. This document does not include an evaluation of these alternatives. For context, a brief history of the NEPA decision-making process that has occurred since the 1990s, a summary of more recent public engagement by the City, and recent direction from the City Council are provided. Any change or deviation from the PA and ROD would require close coordination and agreement from FHWA and CDOT. It also would require coordination with other corridor stakeholders and interests. Therefore, the NEPA decision making will involve other parties besides the City and, because FHWA is the federal lead agency for the ETA EIS, it will have final decision-making authority. 2. Background and History The Entrance to Aspen project has received federal funding and undergone extensive study over the years in compliance with NEPA. This section summarizes the milestones and decisions that have occurred since project initiation. 2.1 History of the EIS CDOT, in conjunction with FHWA, undertook the NEPA process for this project as follows: 1994: NEPA process initiated with extensive public input and supporting technical studies. 1995: Draft EIS (DEIS) released for public review and comment; DEIS evaluated: Three alternatives between Buttermilk and Maroon Creek Road (Area 1) Seven alternatives between Maroon Creek Road and the intersection of 7th and Main Street (Area 2) 1996: Draft Supplemental EIS released (DSEIS); evaluated three additional alternatives between Pitkin County airport and Rubey Park as a result of public/agency comments. 1997: Final EIS (FEIS) released for public review and comment. 1998: Record of Decision (ROD) released; PA is identified as a combination of highway and intersection improvements, a transit system, and an incremental transportation management program (more details in Section 2.2); PA includes constructing a new Castle Creek Bridge to the south and realigning SH 82 in conjunction with extending Main Street to the west. 2007: CDOT and FHWA conducted a reevaluation of the 1997 FEIS/1998 ROD and confirmed that the 1998 ROD PA remained valid. The reevaluation assessed whether: Any changes had occurred in project design concept or scope Any regulatory or environmental changes had occurred since the FEIS and ROD were published Whether those changes would result in any new or additional environmental impacts not previously identified and evaluated in the FEIS 2.1.1 EIS Alternatives Screening Process In compliance with NEPA requirements, a range of reasonable alternatives were evaluated during the EIS process. A range of reasonable alternatives includes those that are “technically and economically feasible, and meet the purpose and need for the proposed action” (40 CFR § 1508.1). This is relevant to the City’s decision-making on next steps for the CCB project because NEPA requirements vary depending on if alternatives were previously considered during the EIS and how far into the evaluation process they were considered. Also, the rationale for eliminating alternatives considered during the EIS process may shed light on their likelihood to be advanced in a new NEPA process. 219 3 In a City Council work session on November 28th, 2022, City staff presented information regarding the alternatives evaluation process that occurred during the EIS process. This information is summarized here; details regarding the alternatives process can be found in the work session packet. CDOT developed options for alignment, laneage, profile, and travel mode. These options were evaluated under three screening levels (reality check, fatal flaw, and comparative) that applied progressively more demanding criteria. Options that passed the reality check and fatal flaw screens were combined to form alternatives for comparative screening. Reality Check: Eliminated options that were clearly unrealistic, inappropriate, or unreasonable due to physical constraints, funding, technology limitations, or impacts on private properties. Fatal Flaw: Eliminated options that did not: o Meet one or more of the 10 community objectives (see inset) o Solve the transportation problems and concerns identified for the project, and/or o Meet the project’s purpose and need Comparative: Eliminated alternatives that were not logical when compared to other alternatives based on analysis of key environmental parameters and issues. The screening results from the 1995 DEIS are summarized in Table 1, along with the rationale for eliminating options from further consideration. Based on results of the alternatives screening, alternatives carried forward for detailed evaluation in the DEIS process included: Area 1: Buttermilk Ski Area to Maroon Creek Road o Alternative 1: No Action Alternative o Alternative 2: Existing Alignment o Alternative 3: Existing Alignment with a separate transit envelope Area 2: Maroon Creek Road to the intersection of 7th Street and Main Street o Alternative A: No Action Alternative o Alternative B: Existing Alignment 2 o Alternative C: Modified Direct alignment at grade o Alternative D: Modified Direct alignment at grade with separate transit envelope o Alternative E: Modified Direct alignment at grade with cut and cover tunnel o Alternative F: Modified Direct alignment, with a cut and cover segment, and with separate transit envelope o Alternative G: Two Improved Lanes on Existing Alignment and Transitway on the Modified direct alignment 3 Figures depicting the Area 2 alternative alignments are included in Attachment 1. 2 Eliminated in comparative screening, but evaluated in DEIS for comparative purposes. 3 Eliminated in comparative screening, but evaluated in DEIS at the request of the City Council. Local community objectives were identified during the EIS process and helped guide alternative evaluation. These include: Community Based Planning Transportation Capacity Safety Environmentally Sound Alternative Community Acceptability Financial Limitations Clean Air Act Requirements Emergency Access Livable Communities Phasing 220 4 Table 1: EIS Screening Results SCREENING LEVEL OPTIONS 1: Reality Check 2: Fatal Flaw 3: Comparative Rationale for Eliminating Alignment2 Denver & Rio Grande Western RR Impacts to adjacent developments. West of Maroon Creek Rd Impacts to adjacent developments (open space). Old Midland RR Extensive disruption to existing developments along Shadow Mountain and within Aspen downtown area. Financial constraints. Impacts to adjacent developments. Existing 4 Community acceptability. Does not significantly improve safety because of existing “S curves.” Does not address the need for alternative emergency access route. Direct Connection (straight shot) Impacts to open space. Lack of community support. Combination (split or couplet using the existing and direct or modified direct alignments)5 Operational problems for Cemetery Lane traffic heading east on Hwy 82 (couplet). Operational problems splitting traffic at 7th Street and Main Street (split alignment). Modified Direct Selected as alignment for the PA. 4 Eliminated in comparative screening, but evaluated in DEIS for comparative purposes. 5 Split Alignment eliminated in comparative screening, but evaluated in DEIS at the request of the City Council. Couplet Alignment eliminated in comparative screening, but evaluated in SDEIS at the request of the City Council. 221 5 SCREENING LEVEL OPTIONS 1: Reality Check 2: Fatal Flaw 3: Comparative Rationale for Eliminating Laneage 2 Highway Lanes Did not meet the capacity requirements for future traffic demand. Did not meet the emergency access objective. Did not provide for future transit options and upgrades that are part of Aspen community plan. 3 Highway Lanes Would not provide the needed future traffic capacity (transit and private vehicles) for both directions of SH 82. Did not meet the phasing objective. Was unacceptable to the community because of the large number of signs required to safely implement and regulate the reversible lane. 2 Highway Lanes + 1 Dedicated Lane Same as 3 Highway Lanes Option. 4 Highway Lanes Did not provide incentive for transit or carpool use considered essential to control traffic growth on SH 82. Not consistent with community-based planning goals. T 2 Highway Lanes + 2 Dedicated Lanes Selected as laneage for the PA. Profile Elevated Unacceptable visual impacts. Tunnel (greater than 700 feet long) Unacceptable cost and construction impacts. Cut and Cover Selected as part of profile for the PA. At-Grade Selected as part of profile for the PA. Mode Unproven Technology In research and development; not in revenue service. 222 6 SCREENING LEVEL OPTIONS 1: Reality Check 2: Fatal Flaw 3: Comparative Rationale for Eliminating Personal Rapid Transit Same as Unproven Technologies. Commuter Rail Did not meet the capacity objective due to inability to operate efficiently in mixed flow traffic conditions. Wire Slope Systems Not acceptable as an in-town transit system visually, operationally, or financially. Guided Busways Did not compare favorably to other bus options for cost, maintenance, and community acceptability. HOV Passed comparative screen and was evaluated in DEIS. Self-Propelled Buses Selected as an initial phase transit mode for the PA. Electric Trolley Buses Passed comparative screen; not selected due to unacceptable visual impacts. Light Rail Transit Selected as final phase transit mode for the PA. 223 7 After the release of the DEIS, three additional alternatives were evaluated in a draft supplemental EIS (DSEIS). In addition to the modified direct alignment with cut and cover tunnel, a couplet alignment (one- way pair) with an at-grade profile was evaluated (Alternative H) along with a phased version of each of these alternatives that allowed for exclusive bus lanes as an interim phase if local support and/or funding is not available for the LRT system. Alternative H included two outbound highway lanes along the existing SH 82 alignment and one inbound highway lane plus the LRT envelope along the modified direct alignment. In the interim version of Alternative H, one vehicle lane and one dedicated bus lane would be implemented in each direction with the SH 82 alignment serving outbound traffic and the modified direct alignment serving inbound traffic. Alternative H (the couplet alignment) was eliminated for the same reason this alignment was screened out in the comparative screening in the DEIS; operational problems. The phased options were eliminated due to lack of support from the community and the City Council. The phased approach was noted as adding cost and having unnecessary disruption to Section 4(f) resources compared to a non-phased approach. This decision regarding phasing was reversed in the ROD, and is included in the PA. 2.1.2 Preferred Alternative The PA is a combination of highway and intersection improvements, a transit system, and an incremental transportation management program. Table 2 lists the various components of the PA. Figure 1 shows the PA components that have been implemented and Figure 2 shows elements of the last major uncompleted phase associated with a new Castle Creek Bridge. Table 2: Elements of the Preferred Alternative Highway Component Transit System Incremental Transportation Management Program Two-lane highway (one lane in each direction) along the existing SH 82 alignment from Buttermilk Ski Area to the Maroon Creek Bridge. Relocate existing Owl Creek Road and West Buttermilk Road to create a new combined intersection at SH 82 near Buttermilk Ski Area. Highway crosses Maroon Creek on a new bridge north of the existing bridge, then return to the existing alignment and continue to roundabout at Maroon Creek Road intersection. East of the roundabout, highway shifts southeast across the Marolt- Thomas property and through a cut-and-cover tunnel 400 feet long to connect with the intersection of 7th Street and Main Street via a new Castle Creek bridge. Light rail (LRT) system on the south side of the highway running between the new LRT maintenance center near Service Center Road and Rubey Park in downtown Aspen. The LRT system will be developed initially as two exclusive bus lanes one in each direction) if local support and/or funding are not available. Doubling of bus service between Aspen and El Jebel. Increased bus service in town and between Aspen and Snowmass Village. Expanded park-and-ride facilities throughout the valley. HOV lanes between Basalt and Buttermilk and preferential parking for HOVs. Rideshare matching program. In-town parking fees. Residential parking permit program, commuter incentive programs, and employer bus passes. 224 8 Figure 1: Preferred Alternative: Completed Improvements and Elements 225 9 Figure 2: Preferred Alternative: Uncompleted Improvements 2.2 Community Support and Sentiment Between 1975 and 2002, voters in Pitkin County and the City of Aspen weighed in on numerous transportation ballot measures pertaining to transit, parking, transportation right-of-way (ROW) across the Marolt and Thomas properties, and implementation of the PA. Votes in the 1970s and 1980s showed support for transit rather than increasing the capacity of SH 82. Five votes in the 1990s yielded mixed results for transit support. Voters expressed concern about traffic impacts if transit options were not expanded. Voters also expressed a preference for use of transit in the valley and use of park-n-rides over expanding parking in Aspen. However, voters were not supportive of funding to develop transit systems. Sentiment on funding transit shifted in 2000, with strong support for 1) a tax measure to establish and fund a regional transit authority and 2) a bond measure that included funding for various bus improvements. Voter opinions about conveying transportation ROW through the Marolt and Thomas properties have been mixed. This subject was put to the voters eight times between 1982 and 2001. Voters were mostly in favor of the 1990 and 1996 ballot measures, while results the other five years showed voters were predominantly opposed. Voter opinions about realigning SH 82 at the entrance to Aspen have shifted over time. A 1990 vote showed strong support for the realignment as opposed to making improvements on the existing alignment. However, a 2002 vote showed support for “S-Curves” over “Modified-Direct.” 226 10 2.3 Recent History/Events 2.3.1 Public Awareness Campaign More than 15 years had passed since the community was engaged regarding the Entrance to Aspen project when, in 2021, the City initiated a program to bring awareness to the community about the history and current state of the existing Castle Creek Bridge and future options for the Entrance to Aspen project. As identified in the New Castle Creek Bridge Awareness Plan Summary | Phase 1 document, the following messages were relayed across communication channels (events, website, presentations, printed material, advertising) during the awareness phase of the project: The Castle Creek Bridge history, service life, and current state of repairs. The Record of Decision, 10 Project Objectives, and a detailed explanation of the Preferred Alternative. Marolt-Thomas Open Space right of way (ROW), land exchange and future opportunities for pedestrian access via a land bridge. This includes a new vote to change ROW usage from light rail to buses. Pros and cons of the Preferred Alternative - “It is not a silver bullet”. If implemented, this project could negatively impact homeowners near the bridge and roadway. Transit-oriented solution that focuses on improved flow and travel times for buses and future technology. None of the 43 alternatives evaluated solve traffic congestion. The Preferred Alternative improves the flow of single occupancy vehicles. The timing of revisiting the project. Importance of improved emergency evacuation and access. The path forward for rebuilding the existing bridge or building the Preferred Alternative. Figure 3 depicts a summary of the primary supports and concerns voiced by the public during the public awareness campaign. The sizes of the circle generally represent the number of comments related to that topic or theme. Details are provided in The New Castle Creek Bridge Awareness Plan Summary | Phase 1 document. This document states: “The majority of those with whom we met felt it was time for a new bridge. Within this group, there were varying opinions about elements of the Preferred Alternative and the best path forward…”. 227 11 Figure 3: Public Support and Concerns 2.3.2 Recent Council Direction Considering the divided community sentiment on the PA, city council opted not to advance implementing the last major PA phase (i.e. realigning SH 82 and constructing a new Castle Creek bridge) at this time. Some council members expressed concern about the impacts associated with this final phase. The city hired Jacobs Engineering to assess options to rehabilitate or replace the existing Castle Creek Bridge and soften the S Curves through town. In spring 2024, Jacobs will provide a report regarding the feasibility of replacement of the existing bridge in its current location, including a proposed schedule and cost for accelerated construction and three-lane bridge construction, in addition to other work to answer community questions that arose during the community awareness effort. The contract scope also includes a pre-NEPA Process Outline, including procedural paths forward considering cost, schedule and risks. 3. NEPA Process Options and Paths Forward This section addresses the following options for moving forward with the CCB project: 1. implement the PA identified in 1998 ROD (interim phase with bus lanes) (Section Error! Reference source not found.), 228 12 2. implement the PA identified in the 1998 ROD with minor modifications (Section Error! Reference source not found.), 3. consider a different alternative than the PA: a. analyze impacts of an alternative or alternatives that had been originally considered previously in the 1997 EIS and were either fully analyzed but not selected as the PA (Section Error! Reference source not found.) or dismissed from analysis (Section Error! Reference source not found.), or b. analyze impacts of one or more new alternatives to identify a new PA (Section Error! Reference source not found.) Table 3 summarizes these options and lists various considerations involved in each. Separately from the options outlined in Table 3, the city could pursue improvements to address safety, congestion, emergency evacuation, and other entrance to Aspen issues. Table 4 includes examples of several improvement options that have been discussed. None of these options would address the issues with the aging Castle Creek bridge. Upon advancing any option, the city would need to provide FHWA and CDOT with documentation regarding how the proposed improvements relate to the PA from the 1998 ROD and explain how the improvement would not deviate or detract from the PA and its intent. 229 13 Table 3: Castle Creek Bridge - NEPA Process Options 6 ROM = Rough Order of Magnitude. ROM estimates for NEPA effort only; does not include final design. ROM estimates can vary considerably based on variables such as types and levels of traffic, design, and environmental analyses, extent of public outreach activities and controversy, and agencies reviews. Estimates intended to generally illustrate costs differences between different NEPA options. NEPA Process Options Examples/Description Clearance Process Approx. Timeline ROM 6 Cost Risks & Other Considerations 1. Implement Existing PA Implement PA (interim phase with bus lanes) • Shift SH 82 to the southeast across the Marolt-Thomas property to connect with the intersection of 7th Street and Main Street. • Construct cut-and-cover tunnel 400 feet long and a new Castle Creek bridge. Implement Bus Rapid Transit (BRT) as interim step to future LRT. Reevaluation 1 year $ 1M This solution was selected by FHWA and endorsed by the City after extensive evaluation and public process as the best option to address the identified community goals Due to amount of time that has passed since ROD, community goals from FEIS/ROD may no longer reflect desires/priorities of current residents. This situation could warrant a new EIS. CDOT has stated no community vote needed to proceed with PA, which includes interim step of BRT; further analysis by the City attorney is needed to confirm if a vote is required before proceeding with BRT. 2. Modify PA Changes result in new significant impact • Minor alignment shift with new significant impact. SEIS/ROD 2 years $2M Due to amount of time that has passed since ROD, community goals from FEIS/ROD may no longer reflect desires/priorities of current residents. This situation could warrant a new EIS. City is responsible for cost of SEIS/Revised ROD Changing original PA decision increases risk of litigation. 230 14 NEPA Process Options Examples/Description Clearance Process Approx. Timeline ROM 6 Cost Risks & Other Considerations Changes result in increased (but not significant), same, or less impact • Separate bridges for highway and LRT using the modified-direct alignment. • Change 24-hour dedicated bus lanes in PA to 24-hour or peak period Bus/HOV lane. • New transportation management options with no new significant impacts. Reevaluation 1 – 1.5 years $1-1.5 M Due to amount of time that has passed since ROD, community goals from EIS/ROD may no longer reflect desires/priorities of current residents. This situation could warrant a new EIS. City is responsible for Reevaluation cost. Changing original PA decision increases risk of litigation. 3. Consider a Different Alternative Consider Alternative Fully Evaluated in EIS • Existing Alignment* (4-lanes) • Modified-Direct, At-Grade* • Modified-Direct, At-Grade with Separate Transit Envelope* • Modified-Direct, Cut-and-Cover Tunnel (no separate transit envelope)* • Two Improved Lanes on Existing Alignment; Transitway on Modified Direct Alignment, At- Grade (Split Alignment) • Two Improved Lanes on Existing Alignment; One Improved Lane plus Transitway on Modified Direct Alignment, At-Grade (Couplet Alignment) * These alternatives consist of two general highway lanes and two dedicated vehicle and/or transit lanes. Revised ROD (with Reevaluation) 1 - 2 years $1-2M Selection of a new alternative would require public involvement and input on reasons for changing alternatives. Due to amount of time that has passed since ROD, community goals from FEIS/ROD may no longer reflect desires/priorities of current residents. This situation could warrant a new EIS. Existing Alignment and Split Alignment were evaluated and did not pass the comparative screening in the DEIS. The existing alignment did not meet needs for safety or emergency access. The Split Alignment had substantial impacts and operational issues. These alternatives were only evaluated for comparative purposes. Alternative may be eliminated for same reasons as identified in FEIS. City is responsible for cost of Revised ROD/Reevaluation. FHWA could request reimbursement for original EIS costs, including mitigation already provided at open space and elsewhere. 231 15 NEPA Process Options Examples/Description Clearance Process Approx. Timeline ROM 6 Cost Risks & Other Considerations Changing original PA decision increases risk of litigation. Consider Alternative Eliminated in Screening Process • Replace existing bridge in-kind (Existing Alignment/2 Highway Lanes) • Three Highway Lanes (Reversible Lane) New EIS/ROD 2+ years $2-3M Given time since ROD, SEIS unlikely. New scoping process will reassess purpose and need, and community goals. Selection of a new alternative would require public involvement and input on reasons for changing alternatives. Alternative may be eliminated for same reasons as identified in FEIS. City is responsible for cost of new EIS/ROD. FHWA could request reimbursement for original EIS costs, including mitigation already provided at open space and elsewhere. Changing original PA decision increases risk of litigation. Risk of lane closures, weight restrictions, or CDOT implementation of PA increases over time due to ongoing deterioration of existing bridge. Consider New Alternative Aspen/Buttermilk Interchange alternative New EIS/ROD 3+ years $3-4M Same as Pursue Alternative Eliminated in Screening, except alternative(s) has not previously been screened and more time is likely required to develop the alternative. 232 16 Table 4: Implement Stand-Alone Improvements - NEPA Process Options + if project is a federal action ^does not address bridge issue 7 ROM = Rough Order of Magnitude. ROM estimates for NEPA effort only; does not include final design. ROM estimates can vary considerably based on variables such as types and levels of traffic, design, and environmental analyses, extent of public outreach activities and controversy, and agencies reviews. Estimates intended to generally illustrate costs differences between different NEPA options. NEPA Process Options Examples/Description Clearance Process Approx. Timeline ROM 7 Cost Risks & Other Considerations Implement Improvements Separate from the PA • S curve softening^ • Maroon Creek Roundabout HOV bypass lane (outbound traffic)^ • Emergency evacuation improvements to existing pedestrian bridge and Power Plant Road^ Categorial Exclusion (CE)+ CE/EA+ CE/ EA+ <1 year 1 year 1-1.5 year 1 year $250- 350K $1M $1M FHWA has confirmed that S Curve softening would not ‘break’ the ROD. Roundabout bypass would require Section 4(f) evaluation and alternatives analysis because of public golf course impacts. CE possible if designed to minimize impacts. 233 17 4. Conclusions Confirming the approach for the final phase of the Entrance to Aspen is time critical as the Castle Creek Bridge nears the end of its service life. Because SH 82 is a state highway managed by CDOT and federal funds have been used to study and build Entrance to Aspen improvements, NEPA and other federal regulations will continue to apply to decision-making regarding improvements at the Castle Creek Bridge. When the bridge condition is rated poor through CDOT inspections, it will enter the Statewide Bridge and Tunnel Enterprise eligibility pool for funding and replacement. At that time, CDOT has indicated it would replace the bridge as directed in the PA, unless an alternate NEPA decision is made prior to the need for bridge replacement. Re-visiting the NEPA process (as outlined in Table 3) would require CDOT and FHWA oversight and participation and would not necessarily result in a different decision than is documented in the 1998 ROD. However, there may be valid reasons to re-visit the NEPA process beyond reevaluating the PA. While the 1998 NEPA decision from the ROD was determined to be valid in 2007, that reevaluation is now 17 years old. The NEPA process options outlined in Table 3 are based on federal regulations, however, the amount of time that has passed may warrant a new NEPA process to solicit input from current stakeholders and the general public regarding issues to be addressed and alternatives for consideration. This is referred to as project scoping and generally occurs early in a NEPA process or as part of a pre-NEPA process. A refresh of earlier project scoping would enable current residents and users of SH 82 to have a voice in the transportation solutions for the Entrance to Aspen. This approach would address the mixed public support and sentiment regarding the PA expressed through multiple votes over the years and a 2021 public awareness campaign. During a March 5, 2024 meeting to discuss NEPA process options, FHWA acknowledged that a new NEPA process may be warranted to refresh project scoping efforts. There is considerable merit to initiating project scoping outside a formal NEPA process. This approach would leave the ROD intact while the Council considers its options and would help to meet required NEPA processing timelines. NEPA regulations were amended in 2021 to include a one-year maximum for EAs and a two-year maximum for EISs. Given the potential for public controversy surrounding alternatives to improve the Entrance to Aspen, these timelines may be very difficult to achieve. Pre-NEPA studies to meet these deadlines, and confirm the NEPA class of action before initiating a NEPA process, have become increasingly common. If the City, in coordination with CDOT and FHWA, determines a new NEPA process is warranted, an early alternatives analysis would position the City to meet the NEPA deadlines and provide better information for FHWA to determine the NEPA class of action (EA vs. EIS). Examples of new or updated information that could inform decision making include traffic modelling and updated historic resources data. After considering public input and alternatives, if pursuing the PA is the desired outcome, this pre-NEPA work would be used in the EIS reevaluation. 234 18 Attachment 1: Alternative Exhibits from FEIS 235 19 Alternative B: Existing Alignment 236 20 Alternatives C, D, E, F: Modified Direct Alignment 237 21 Alternative G: Improved Existing Alignment and Transitway on Modified Direct Alignment 238