FEASIBILITY STUDY UPDATE State Highway 82 – Maroon Creek Roundabout to Main Street Reversible Lane Aspen, Colorado
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FEASIBILITY STUDY UPDATE State Highway 82 – Maroon Creek Roundabout to Main Street Reversible Lane Aspen, Colorado Prepared for: The City of Aspen Pitkin County Aspen, Colorado Prepared by: Schmueser Gordon Meyer 118 West 6th, Suite 200 Glenwood Springs, Colorado 81601 Original: January 2008 Update: May 2008 SH 82 – Maroon Creek Roundabout to Main Street Reversible Lane Feasibility Study Update FEASIBILITY STUDY UPDATE STATE HIGHWAY 82 – MAROON CREEK ROUNDABOUT TO MAIN STREET REVERSIBLE LANE Aspen, Colorado CONTENTS EXECUTIVE SUMMARY 1 1.0 INTRODUCTION 3 1.1 Project History and Need 3 1.2 Purpose and Scope of Feasibility Study 3 2.0 EXISTING CONDITIONS 6 2.1 Project Corridor Existing Conditions 6 2.2 Castle Creek Bridge Existing Conditions 7 3.0 REVERSE-FLOW ROADWAY CHARACTERISTICS 8 3.1 Reverse-Flow Fundamentals 8 3.2 Reverse-Flow Traffic Control Devices 8 3.3 Reversible Lane Feasibility Conditions 10 3.4 Reversible Lane Evaluation 12 4.0 EXISTING CASTLE CREEK BRIDGE 14 4.1 Site Constraints 14 4.2 Site Opportunities 15 4.3 Utilities, Easements and ROW 15 5.0 BRIDGE MODIFICATIONS AND LIMITATIONS 17 5.1 Caveats to Design Recommendations 17 5.1.1 HS25 Design Live Loading 17 5.1.2 Designing for a New Hydraulic Event 17 5.1.3 Evaluation of Environmental Impacts 18 5.2 Increased Length at Pier Cap to Expand Roadway Width 18 5.3 Bearing Issues at Footings and Abutments 18 5.4 Constructability Review 19 5.5 Summary of Possible Bridge Expansion 20 REFERNCES APPENDIX i SH 82 – Maroon Creek Roundabout to Main Street Reversible Lane Feasibility Study Update LIST OF FIGURES AND EXHIBITS Figure P1. Reversible Lane Alternative – Cemetery Lane Updated Figure P2. Reversible Lane Alternative – 7th St & Hallam St Updated Figure P3. Reversible Lane Alternative – 7th Street & Main St Updated Figure S1. Existing Bridge Sections Figure S2. Proposed Bridge Sections – North Expansion Figure S3. Proposed Bridge Sections – Symmetric Expansion Exhibit A. Preliminary Opinion of Probable Construction Costs ii SH 82 – Maroon Creek Roundabout to Main Street Reversible Lane Feasibility Study Update FEASIBILITY STUDY UPDATE STATE HIGHWAY 82 – MAROON CREEK ROUNDABOUT TO MAIN STREET REVERSIBLE LANE Aspen, Colorado EXECUTIVE SUMMARY Update May 2008: This update to the Feasibility Study (dated January 2008) stems from comments made by members of City Council in the February 19, 2008 work session. Initially, this study assumed that the Castle Creek Bridge widening would occur symmetrically about the existing bridge centerline, in order to minimize Right-of-Way impacts on adjacent properties. Council’s primary direction was to remove the ROW constraint from the study to reduce construction delays and duration. This concept allows the bridge expansion to occur solely on the north side of the existing structure, while maintaining two-way traffic on the current alignment during the majority of a relatively shortened construction period. The savings in the construction timeframes could potentially be offset in additional time necessary for right-of-way acquisitions necessary for this option. A reversible lane along State Highway 82 from the Maroon Creek roundabout to the intersection of Seventh and Main in Aspen would be the first of its kind in Colorado. Although some contra-flow lanes exist along the Front Range, this would be the first location in Colorado having a reverse-flow lane on a low-speed arterial facility. Reversible lanes have been in operation for years in many areas of the country, typically in suburban and urban environments where there is a substantial peak directional commuter pattern. This feasibility analysis describes the basic fundamentals of reversible lane operations, key components of the reversible lane system, the required structural modifications to the Castle Creek Bridge and a preliminary cost estimate for the bridge widening and traffic signal equipment and associated line items necessary to operate a reversible lane from the Maroon Creek Roundabout to Seventh and Main. The concept of a reversible lane has been identified in the Entrance to Aspen Final Environmental Impact Statement supporting documentation but its alignment did not meet all of the selection criteria and it was deemed a rejected alternate. This alternative gained revived interest when the City of Aspen created the “S-Curves” Task Force in 2003 to investigate interim solutions until the Entrance to Aspen was fully funded. While this Task Force also deemed this possible solution as an unobtainable interim goal, interest continued in this possible solution. This study reviewed the SH 82 corridor for the traffic operational feasibility of reversible lanes. Of the eight corridor conditions that should be present when considering a reverse- flow system, the project on the SH 82 corridor generally meets five of the eight conditions. This would imply that that area has merit for consideration; however it does not imply that it is ideal for this traffic solution because of the significance of the conditions not met. - 1 – SH 82 – Maroon Creek Roundabout to Main Street Reversible Lane Feasibility Study Update A critical component to this application is the expansion of the existing Castle Creek Bridge to allow a third travel lane across it. If CDOT will allow an expansion of this bridge using the original design parameters (traffic loading, hydraulic events, etc) then it would be possible to widen the existing pier to support additional road deck section. If CDOT requires the planned structural modifications to include current bridge design standards, we believe that it would be more feasible to completely remove and replace the existing Castle Creek Bridge. Because this feasibility report would require in depth interaction with CDOT and possible additional work associated with the Reevaluation of the Entrance to Aspen, an exact determination from CDOT on bridge modifications can not be determined without further advancement of this feasibility study. - 2 – SH 82 – Maroon Creek Roundabout to Main Street Reversible Lane Feasibility Study Update FEASIBILITY STUDY UPDATE STATE HIGHWAY 82 – MAROON CREEK TO MAIN STREET REVERSIBLE LANE Aspen, Colorado 1.0 INTRODUCTION 1.1 Project Description and Need A reversible lane along State Highway 82 from the Maroon Creek roundabout to the intersection of Seventh and Main in Aspen would be the first of its kind in Colorado. Although some contra-flow lanes exist in the Denver metro area, this would be the first location in Colorado having a reverse-flow lane on a low-speed arterial facility. Reversible lanes have been in operation for years in many areas of the country, typically in suburban and urban environments where there is a substantial peak directional commuter pattern. This feasibility analysis describes the basic fundamentals of reversible lane operations, key components of the reversible lane system, the required structural modifications to the Castle Creek Bridge and a preliminary cost estimate for the bridge widening and traffic signal equipment and associated line items necessary to operate a reversible lane from the roundabout to Main and Seventh. In 2007 CDOT conducted a Reevaluation of the Entrance to Aspen Final Environmental Impact Statement and Record of Decision initially approved in 1997. The findings for this Reevaluation deemed that the original conclusions were still applicable today, and the preferred alignment remains the primary choice. This feasibility study is being done independent of the Reevaluation and could contain components that do not fully meet the assessment criteria in selecting the preferred alignment. Coordination has been conducted with CDOT staff on an informational basis only for this study and further advancement of this feasibility report would require in depth interaction with CDOT and possible additional work associated with the Reevaluation. This study does not attempt to address any of the discussion in the Reevaluation or previous Entrance to Aspen documents. 1.2 Purpose and Scope of Feasibility Study The City of Aspen Transportation Department has asked Schmueser Gordon Meyer (SGM) to conduct a feasibility study to assess the implementation of a reversible center lane on State Highway 82 through the “S Curve Area” and an expansion of the bridge over Castle Creek (Castle Creek Bridge). The technical analysis of a bridge expansion feasibility study is being done in conjunction with a feasibility study to assess the potential for the addition of the reversible center lane and associated roadway expansions and improvements in the corridor. - 3 – SH 82 – Maroon Creek Roundabout to Main Street Reversible Lane Feasibility Study Update The concept of a reversible lane had been identified in the Entrance to Aspen Final Environmental Impact Statement supporting documentation but its alignment did not meet all of the selection criteria and it was subsequently rejected as a potential alternative. This alternative gained revived interest when the City of Aspen created the “S- Curves” Task Force in 2003 to investigate interim solutions until the Entrance to Aspen was fully funded. While this Task Force also deemed this possible solution as an unobtainable interim goal, interest continued in this possible solution. Listed below are the outcomes listed from the task force pertaining to potential three lane configurations. Three-Lane, Reversible Lane Alternative Opportunities • Improved peak hour capacity during peak hours. • Maximizes the utilization of existing pavement with minimal bridge deck expansion. • Minimal curve softening will not require relocation of structures. • Potential additional landscaping replacement. Constraints • Structural modifications to the existing bridge will be required. • Operation may be confusing for visitors and others new to the operation. • Will require restricting Cemetery Lane to right-in/right-out movements during times the reversible lane is in use. If full movements are maintained at Cemetery lane during peak periods, movable barriers or delineators would have to be manually employed on a daily basis. • Traffic movements crossing the reversible lane at the Seventh/Main Street intersection would need to be prohibited during reversible lane operations.