West Seattle High-Rise Bridge Safety Project Press Briefing *Embargoed Until April 15, 2020 at 3:30pm* Sam Zimbabwe, Matt Donahue and Heather Marx Department April 15, 2020 of Transportation Presentation overview • Background and what has changed since March 23 • Future of the bridge remains uncertain • Stabilization and shoring, tentative schedule • Phase I: Slow or halt bridge deterioration • Pier 18 stabilization and repairs • Phase II: Shoring the bridge • Phase III: Bridge repairs • Technical Advisory Panel • Order of magnitude budget Department of Transportation 2 Background and what has changed Background • Bridge closed on March 23 due to rapid growth in cracking along the center section of the bridge Recent findings • Recent inspections have found cracks continue to grow, but at slower rate, confirming immediate removal of live load was essential • Crews are inspecting the bridge for new and growing cracks each day • The bridge is safe for crews to work • SDOT has a better understanding of stabilization timeline, but there is still uncertainty Department of Transportation 3 Safety is top priority • SDOT continues to inspect the bridge daily • We are installing intelligent monitoring equipment to monitor any changes to the bridge in real time, with 24/7 alerts • We are modeling potential cracking scenarios and preparing contingency plans • These plans will enable rapid response to preserve public safety Department of Transportation 4 Future of the Bridge Remains Uncertain • SDOT does not yet know if repair of the bridge is feasible technically or financially • If repair is feasible, it could provide up to 10 years of additional use • We will need to replace the West Seattle High Bridge, the question is when • We do not anticipate traffic returning to the bridge in 2020 or 2021 • We are committed to clear communication and transparency throughout Department of Transportation 5 Stabilization and shoring schedule • Ongoing—Continue field inspection and install instrumentation hardware/real time alerts • Immediately—Pier 18 restraint release design • Spring—Shoring and repair design begin, technical advisory panel for peer review launched • Summer—Pier 18 restraint released; shoring materials procurement begins • Late Fall—Shoring construction begins • Early Spring 2021—Shoring construction complete Department of Transportation 6 Phase I: Slow or halt bridge deterioration • On March 23, SDOT discovered new cracking, confirming growth had rapidly increased over the prior two weeks • Cracking has slowed since we removed live load, indicating that removing the weight of traffic has helped prevent worse damage • Stabilization is intended to slow or stop the cracking and preserve the integrity of the bridge • Next steps: continue to assess repair feasibility, timeline, and costs Department of Transportation 7 What is a lateral bearing? • Bridge bearings sit between the bridge’s roadway and the support piers holding it up • Bearings allow the bridge to be move in response to traffic, normal concrete creep and shrinkage, thermal variations • Pier 18 bearings are compressed and bulging, creating additional pressure and affecting the whole bridge Department of Transportation 8 Stabilization through Pier 18 repairs • To slow cracking, unlocking Pier 18 lateral bearing is the top priority for repair • Repairing the locked bearing is contingent on bridge strength analysis to determine if the bridge can handle the stress • SDOT is procuring a contractor to perform these immediate emergency repairs Department of Transportation 9 Phase II: Shoring the bridge to further stabilize • The process of “shoring” means adding temporary support to the bridge to preserve its integrity and enable repairs • Mid-2020 – obtain and build specially fabricated materials for shoring while Pier 18 repairs are made • Late 2020 – Shoring Construction Department of Transportation 10 Phase III: Bridge Repair Key elements of uncertainty right now: • Can bridge be stabilized before further deterioration makes repair infeasible? • Will repair require permits to impact the navigation channel? • Will repair require special fabrication or equipment? • Is repair feasible technically or financially? Department of Transportation 11 Phase III: Bridge Repair • Repair of the West Seattle Bridge may not be possible • We are at 0 percent design, and each step will impact what’s feasible and how long it will take • If repair is possible, we anticipate it could provide up to 10 years of additional use Department of Transportation 12 Establishing Technical Advisory Panel • The condition of the West Seattle High Bridge and the complexities of monitoring, design, and repair are complex • The Technical Advisory Panel will provide qualitative review, insight, constructive feedback, and validation • The Panel will consist of experts with experience in bridge design and construction, geotechnical engineering for bridge structures, and marine/maritime expertise Department of Transportation 13 Traffic Mitigations • Closing the West Seattle Bridge has a similar level of complexity to our recent Viaduct closure, but with fewer re-route choices, and shorter timeline • Low Bridge restricted to people driving emergency vehicles, freight trucks, and public transit • Seattle Police Department is supporting enforcement • Path open to people walking and biking • Access to Harbor Island for general public via east channel bridge Department of Transportation 14 Traffic Mitigations • Traffic signal installed at Highland Park Way SW and SW Holden St • Detour route signage to 1st Ave S Bridge improved • Signals at the five-way intersection connected to citywide system for remote monitoring adjustment. Repave intersection. • Stripe, sign, and smooth alternative routes • Additional measures to be identified Department of Transportation 15 Order of magnitude budget through shoring Action Monitoring* Design* Pier 18 repair construction Shoring construction Traffic control and mitigations* Project Management, Communications, and outreach Swing Bridge Maintenance* Total Repair Department of Transportation 16 Estimated Cost $2,000,000 $6,000,000 $1,000,000 $15,000,000 $3,000,000 $1,000,000 $5,000,000 $33,000,000 TBD * Portions of these costs included in current programmatic budgets, but other deliverables may be affected Bringing Community Together • Work with West Seattle community and businesses to keep people informed, provide resources, and answer questions • Share email updates with 1,000+ subscribers so they hear from SDOT about what's happening and how to get around • Post blogs, new maps and graphics to help with commuting, and answers to important questions online • Work closely with media, sharing news and answering questions for broader audiences • Continue to build partnership with Department of Neighborhoods and Office of Economic Development to reach out to the broader community, freight, and maritime communities Department of Transportation 17 Questions / Discussion www.seattle.gov/transportation/westseattlebridge Department of Transportation 18