SDOT updates stabilization work on West Seattle Bridge
information from Seattle Department of Transportation
This past week, we reached a significant milestone by starting to stress the installed post-tensioning system. This coming week, the contractor is planning to:
- Release the restrained bearing at Pier 18
- Begin constructing a new bearing for Pier 18
- Perform the final 100% stressing of the post-tensioning system
- Begin the final phase of carbon fiber exterior girder strengthening
Kraemer North America, our contractor for the stabilization work, is working Monday through Saturday from 6 AM to 4:30 PM every week to stabilize the bridge.
Stabilizing the High-Rise Bridge is necessary to preserve public safety and the integrity of the bridge so that all options remain on the table with the approaching repair or replace decision. Stabilization puts us on the right path if repair is determined to be the best option and helps prevent further crack growth. Stabilization is also necessary for safe demolition if we choose to replace the bridge.
We expect to complete stabilization work by the end of this year. This work includes carbon fiber wrapping weakened areas of the bridge, adding post-tensioning inside the girders, and injecting epoxy into cracks wider than 0.3 mm. The epoxy injections don’t stabilize the bridge; they help prevent further deterioration by protecting the post-tensioning steel inside from corrosion. Monitoring and inspection activities will continue after stabilization work is complete, in both the repair and replacement scenarios.
After the Pier 18 release and post-tensioning are complete, Kraemer North America will do other stabilization work, including applying the final layers of carbon fiber wrap to the girders and rebuilding the lateral bearing at Pier 18. Once all stabilization work has been finished, we will lower the work platforms onto barges and remove other temporary work structures – likely before the end of the year.
While the majority of the traveling public will see little to no traffic impacts during Pier 18 work, there may be lane reductions on Klickitat Ave SW and SW Klickitat Way on the west and south sides of Harbor Island. Please obey the traffic control signs and devices and do not attempt to move them. Our teams are coordinating closely with the Port of Seattle to mitigate traffic impacts.
Over the past few weeks, we have:
- Stressed the post-tensioning system to 10%
- Poured concrete for the deviator blocks, which will keep the post-tensioning strands from touching the bottom of the girder as they travel between anchor locations
- Installed the post-tensioning brackets
- Begun Pier 18 work, including core drilling and wire sawing
- Continued monitoring and inspection efforts