7b Presentation West Seattle Bridge Update
Item No. 7b_supp Meeting Date: May 12, 2020 West Seattle Bridge Update Staff Briefing May 12, 2012 Overview Introduction City of Seattle Presentation by Seattle Department of Transportation (SDOT) External Engagement Internal Working Groups Next Steps Questions 2 Introduction Background Why it matters SDOT's "West Seattle High-Rise Bridge Safety Project" 3 West Seattle High-Rise Bridge Safety Project Port of Seattle Commission Sam Zimbabwe and Heather Marx May 12, 2020Department of Transportation Presentation overview Background and what has changed since March 23 Future of the bridge Traffic Mitigation Communication and outreach Department of Transportation 2 Bridge Background and Details Opened for use in 1984 Cast-in-place concrete and steel bridge One-of-a-kind, uniquely designed for our 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 3 What has changed since March 23, 2020 Background Bridge closed on March 23 due to rapid growth in cracking along the center section of the bridge The bridge was built to the standards, and using the best computation methods, of the day Recent findings Recent inspections have found cracks continue to grow, but at slower rate, confirming immediate removal of live load was essential SDOT has a better understanding of stabilization timeline, but there is still uncertainty Department of Transportation 4 Safety is top priority SDOT continues to inspect the bridge daily Bridge is safe for crews We are installing intelligent monitoring equipment to alert us to any changes in the bridge in real time We are modeling potential cracking scenarios and preparing contingency plans These plans will enable rapid response to preserve public safety We are working with the Port, NWSA, SPD, SFD, the Coast Guard, Army Corps and others on a safety management plan Department of Transportation 5 Be prepared, sign up for AlertSeattle today AlertSeattle is the official emergency notification system used by the City of Seattle to communicate with city residents during emergencies Sign up at alert.seattle.gov to receive free alerts from the City via text message, email, voice message or social media Department of Transportation 6 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 do not anticipate traffic returning to the bridge in 2020 or 2021 We are committed to clear communication and transparency throughout Department of Transportation 7 Stabilization and shoring schedule OngoingContinue field inspection and install instrumentation hardware/real time alerts ImmediatelyPier 18 restraint release design SpringShoring and repair design begin, technical advisory panel for peer review launched SummerPier 18 restraint released; shoring materials procurement begins Late FallShoring construction begins Early Spring 2021Shoring construction complete Department of Transportation 8 Phase I: Slow deterioration & plan next steps On March 23, SDOT discovered the rapid growth of previously observed cracking. Cracking has slowed since we removed traffic. A new intelligent monitoring system will help us identify why the bridge is cracking and serve as an early-warning system if the bridge seems likely to fail. SDOT procured Kraemer North America to perform immediate emergency repairs, including: Temporary crack arrest measures, such as carbon fiber wrapping, to stabilize the bridge and slow deterioration. Repair of Pier 18's lateral bearings; they are compressed so that the bridge cannot move as it is designed to do. This is affecting the whole bridge and contributing to abnormal cracking. Department of Transportation 9 Stabilization through Pier 18 repairs To slow cracking, unlocking Pier 18 lateral bearings is the top priority for repair Repairing the locked bearings is contingent on bridge strength analysis to determine if the bridge can handle the stress SDOT procured Kraemer North America to perform these immediate emergency repairs Department of Transportation 10 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 design shoring system; obtain and build specially fabricated materials for shoring while Pier 18 repairs are made. Late 2020 Shoring construction. Department of Transportation 11 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? We are at 0 percent design, and each step will impact what's doable and timeline Department of Transportation 12 Traffic Mitigations Low Bridge 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 13 Traffic Mitigations Detour Routes Traffic signal installed at Highland Park Way SW and SW Holden St Improved detour route signage Repaved the 5-way intersection west of the Spokane Street/Low Bridge Added six real-time cameras to traffic locations Adjusted signal timing at 13 intersections Installed three dynamic message signs to display travel times via West Marginal Way Department of Transportation 14 Significant change in travel lanes With the High Bridge closure, we've lost 9 traffic lanes of capacity. Transit service capacity is limited by social-distancing requirements We need more options to move West Seattle commuters on and off the peninsula Plus strategies to maintain freight and urban goods and manage cut-through traffic SDOT, Metro and the Port are identifying projects Private business and mobility providers are needed as partners to bring options to the table Department of Transportation 15 How will we move people? Current traffic management improvements: Operational improvements on detour routes signals, traffic monitoring, potholes, rechannelization DRAFT Traffic mitigation plans by June 30 for public input Neighborhoods affected by cut-through traffic Freight Bicycles West Seattle travelers Department of Transportation 16 Traffic Mitigation Potential Strategies Transit service and route changes Carpools and Vanpools Telework and flexible work schedules Employer Shuttles post COVID West Seattle work sites Strategies to improve bicycle use Curbside and parking management Waterbourne transit frequency and Construction management access And what else? First and last mile connections shuttles, park-and-rides, micro- mobility Department of Transportation 17 Communication and Outreach Work closely with the Port of Seattle and the Northwest Seaport Alliance to engage maritime and industrial stakeholders, inform emergency contingency plans and identify traffic mitigation strategies Work with West Seattle, South Park, Georgetown and SODO communities and businesses to keep people informed, provide resources, and answer questions Host monthly Maritime Industry Town Halls with Port and NSWA Share email updates with subscribers so they hear from SDOT about what's happening and how to get around Publish regular blog updates to keep people informed Department of Transportation 18 External Engagement The interagency structure used under the Alaskan Way Viaduct Replacement Program is being reconfigured to support the WSB response/replacement: Executive Oversight; Interagency Leadership; Communications Group; Traffic and Operations; Performance Monitoring In addition, other efforts already underway: Twice Weekly Interagency Check-in Emergency Continency Planning Maritime and Industrial Stakeholder Facilitation West Seattle, South Park, Georgetown and SODO Engagement 22 Internal Working Groups Executive Committee: ensure Port and NWSA senior management is well informed and can provide regular input as the response and replacement process unfolds. Emergency Contingency Planning: support the City led interagency task force in establishing a safety management plan in the unlikely event of a catastrophic failure of the high bridge. Operational Strategy and Performance Monitoring: serve as a clearing house, collecting and developing the data and analysis that will be needed to work productively with the City to ensure adequate landside access and egress for Port and NWSA facilities beyond emergency/contingency planning. Water Transportation: draft proposal as to how the Port and NWSA can support the broadened movement of people and goods via water routes. 23 Internal Working Groups continued Transit: coordinate strategy with external partners on expanded transit needs in light of the closure (e.g. working with Metro for additional stop near Harbor Island) and provide guidance around Port/NWSA employee mobility needs. Replacement Strategy: prepare and, upon approval, execute the strategy around Port/NWSA support for the WSB repair/replacement. Outreach and Communications: set the recommended strategy for external outreach and communications activities. 24 Next Steps Recommended strategies and tactics to Commission and Executive Continued outreach and communications to maritime and industrial stakeholders as well as to impacted communities in partnership with the City (e.g. South Park, West Seattle, Georgetown, SODO) Continued interagency engagement at all levels of the response Future briefings 25 Questions? 26
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