As we advance work to repair the West Seattle Bridge, we’re continuing to plan for an eventual replacement to make the most of what we’ve learned and efficiently invest in our city’s future

West Seattle Bridge. Photo credit: SDOT Flickr.

Summary

  • We continue to plan to eventually replace the West Seattle High-Rise Bridge so we will be ready when the current bridge nears the end of its useful life around 2060.
  • In November 2020, Mayor Durkan made the decision to repair the high bridge and instructed SDOT to continue planning for an eventual replacement of the bridge.
  • We will examine four replacement concepts in different locations near the bridge.
  • At the same time, we are continuing our work on Reconnect West Seattle.
  • You can expect to learn more about what we learn from our September replacement concept location investigation.

As we continue to repair the West Seattle High-Rise Bridge, we continue to plan for an eventual replacement of the high bridge so that we will be ready when the current bridge nears the end of its useful life around 2060.

For over a year now, we’ve been making steady progress in repairing the West Seattle Bridge. In late 2020, we completed emergency stabilization measures that successfully prevented the cracks from growing and kept the bridge in good shape by installing 10 miles of steel cable in the bridge, repairing deformed bearings in the support structure of Pier 18, and wrapping the structure in carbon fiber. We have since had extensive monitoring of the bridge, which has confirmed that the bridge is performing as expected and has allowed us to plan the final phase of repair in the near future.

With all of these advances, now is the time to plan its future replacement, explore location options, and anticipate the future mobility needs of this critical corridor. This work now enables us to carry on what we have learned from the current closure about the importance of people and goods in and through the Duwamish Valley. The research into future replacement options now enables us to work closely with agency partners when preparing investments in the bridge area.

Historically, the high bridge is the city’s most-used main road and carries more than 100,000 travelers every day, including 19,000 bus drivers.

West Seattle Bridge. Photo credit: SDOT Flickr.

In November 2020, Mayor Durkan made the decision to repair the high bridge after in-depth consultation and analysis by SDOT’s structural team, members of the West Seattle Bridge Community Task Force, SDOT’s Technical Advisory Panel made up of leading experts in their field and countless others. This continuous work that has been carried out on, under and within the bridge since March 2020. City, region and state.

At that time, the mayor also instructed SDOT to continue planning for a possible replacement of the bridge. While we are confident that the planned repairs will ensure the operation of the repaired bridge for up to 40 more years, it is important that we consider where a full replacement could fit into this narrow corridor.

The closure of the elevated bridge provides an opportunity to explore future replacement concepts to ensure we are ready when it is time for an eventual replacement.

Replacing an existing bridge is difficult while it is open to travelers. According to the most recent experience, maintaining mobility during the construction phase will be an important goal. As we develop and evaluate concepts for the location of a replacement bridge, we will consider ways to improve and connect the existing corridor using previous and planned investments.

Another part of the preparation includes developing an emergency plan in case we need to react quickly in the unlikely event of another emergency. This work builds on the findings of the cost-benefit analysis. Evolving this contingency plan will save us time and money, and will put us in a better position to expedite approval and identify funding when needed.

We will examine four replacement concepts in different locations near the bridge.

Long-term planning for replacement concepts will consider potential locations on or near the elevated bridge to reduce delays and impacts on communities and travelers during construction. Photo credit: SDOT.

These replacement concept locations are to the north and south of the bridge, in line with the existing bridge, and below in a tunnel.

During the process of defining and evaluating these concepts, we will:

  • Continue to work with the community to validate our understanding of the mobility needs in West Seattle and the Duwamish Valley.
  • Close coordination with neighboring projects in order to consider possible effects and opportunities for cooperation.
  • Develop criteria for evaluating the replacement concepts, similar to what we did in our cost-benefit analysis
  • Evaluate the opportunities and challenges of our replacement concepts based on the criteria
  • Analyze the need for space for pedestrians, cyclists or people taking a seat on a future high bridge replacement and, if necessary, conduct a feasibility study to see if this is possible
  • Provide a summary of the possible replacement locations that should be considered in future planning

At key study milestones, we will share our progress with community members and the public to keep everyone updated and answer questions.

At the same time, we are continuing our work on Reconnect West Seattle. This work began with a community-led process in the summer of 2020 to learn how we can help reduce the impact of the bridge closure and increased traffic in nearby neighborhoods.

Last summer, we collected survey responses from over 17,000 people to learn more about how they travel to, from and around the West Seattle Peninsula. Together, this effort helped us prioritize immediate needs and plan projects for the next year that will better serve the community in the long term. Check out our latest update on Reconnect West Seattle.

You can expect to learn more about what we learn in September as we investigate the locations of the replacement concept.

At the end of this year we will publish the full report on our findings and make recommendations as to which location is preferred for our future replacement.

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