West Seattle High-Rise Bridge Safety Program Photo by Life As Art - PowerPoint PPT Presentation

West Seattle High-Rise Bridge Safety Program Photo by Life As Art used under CC Sound Transit Executive Committee Department of Transportation Sam Zimbabwe, Heather Marx June 11, 2020

Presentation overview • West Seattle High Bridge Status • Emergency contingency planning • Repair phases and options • Upcoming Decisions • Coordination with Sound Transit to date • Managing Traffic Department of Transportation 2

West Seattle High Bridge Safety Project priorities 1. Public safety 2. Urgency to return traffic to WSHB 3. Traffic mitigation while the bridge is closed 4. Stabilizing and shoring the WSHB 5. Closely monitoring and maintaining the Spokane Street Low Bridge 6. Assess repair feasibility, timeline, and costs for the WSHB 7. Clear communication and transparency Date (xx/xx/xxxx) Department Name Page Number 3

Bridge Background and Details • Opened in 1984 • Cast-in-place concrete and steel bridge • One-of-a-kind, uniquely designed for topography and geography • Designed for three lanes in either direction • Highest daily traffic volumes among SDOT roadways • 84,000 vehicles (2019) • 17,000 transit riders This Photo by Unknown Author is licensed under CC BY-SA Department of Transportation 4

Safety is top priority • Recent inspections have found cracks continue to grow, but at slower rate, confirming immediate removal of live load was essential • Intelligent monitoring equipment monitors changes to the bridge in real time, with 24/7 alerts • Potential cracking scenarios modeled through a Critical Failure Analysis • Emergency Contingency Plans developed in the event of failure Department of Transportation 6

SDOT Three-Phase Approach to WSHB assessment and repairs • Phase 1: Slow deterioration, assess problem, immediate repairs • Phase 2: Shore and stabilize WSHB and Pier 18 • Phase 3: Repair Bridge and begin longer term solutions Department of Transportation 7

Moving Ahead on Multiple Paths Bridge Activities Since the Closure • Installed monitoring instrumentation • Secured a contractor to complete bridge stabilization • Continuing to monitor cracking • Pier 18 repair construction planning • Issued an RFQ for a design consultant to consider type, size and location structures in the event of replacement Department of Transportation

Department of Transportation

Request for Qualifications – issued June 2 • Invites design teams to show their qualifications to design bridge replacement • Structured to allow maximum flexibility for timing, cost and replacement type (includes both bridge and tunnel types) • If repair is possible, then the design team will work on the longer-term replacement • If repair is not possible, the design team will be already be on board to save time • Rehabilitation and retrofits design for structures on either side may be included • Current area to be evaluated is between SR99 and W Admiral Way • Team expected to be on-board in October Department of Transportation

WSB Project Milestones January 2021 September November September November December December February October October August August March June June April July May July Initial Decision: Replacement Program Bridge Demolition Repair/Replacement Bridge Repair/ Demolition (if repl ) Repair Pier 18 Release Replacement Temporary Crack Arrest Shoring Community Task Force & TAP Draft Final Action Plan & Implementation Strategies Traffic Mitigation Community-Led Prioritization Council Mayor’s PSRC Federal Adoption Project Finance 2020- Legislative Session Planning BUILD Grant 2020-2021 2021 Grant Budget Budget Council Council Council Council Council Council Council Council Mayor/ Briefing Briefing Briefing Briefing Briefing Briefing Briefing Briefing Council Actions City’s Legislative CIP established Agenda Department of Transportation 10

WSBLE DEIS Duwamish Crossing Alternatives Section of WSHB that needs repair DUW-2 Insert readable map DUW-1a DUW-1b 5/19/2020 Department of Transportation 11

Coordination with Sound Transit To Date • Joint Sound Transit/SDOT Engineering Work Session on April 30 • Examined whether a combined light rail and vehicle bridge over the Duwamish could be practical from an engineering design perspective • Potential next steps: • in depth study of loading and geometry • consider if practical from perspectives of environmental review, schedule, construction coordination, cost, etc. • set up formal coordination between Sound Transit and West Seattle Bridge capital project delivery Department of Transportation 11

Questions / Discussion Department of Transportation