SDOT offers an update Bridge stabilization; Release of stuck bridge bearing coming soon
Information from Seattle Department of Transportation
The Seattle Department of Transportation is continuing its High-Rise Bridge stabilization efforts.
Stabilizing the High-Rise Bridge is necessary to preserve public safety and the integrity of the bridge so all options remain on the table for a 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.
Kraemer North America, our contractor for the stabilization work, is working every week, Monday through Saturday from 6 AM to 4:30 PM, to stabilize the bridge.
We expect that stabilization work will be complete by the end of the year. The work includes carbon fiber wrapping weakened areas of the bridge, adding post-tensioning inside the girders, and injecting epoxy into cracks that are wider than 0.3mm. 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.
This coming week, the contractor is planning to:
- Finish installing and testing the post-tensioning system
- Mobilize for the Pier 18 release
- Release the restrained bearing at Pier 18 as soon as the end of the week
During daily work, you will see some crews working on top and under the bridge. You will also see scaffolding and crews working on platforms suspended under the bridge. You may also see large equipment and vehicles delivering, moving, and storing materials.
There is also work taking place inside the bridge that you will not be able to see. That work includes monitoring cracks and installing the additional post-tensioning strands. We do not anticipate any additional traffic impacts from this work over the next few weeks.
While we do not anticipate significant impacts to traffic below the bridge, you may see some traffic control signs and devices. These signs and devices are meant to keep the workers and traveling public safe. Please obey the signs and do not move them.
After the Pier 18 release and post-tensioning are complete, Kraemer North America will do other stabilization work including applying additional layers of CFRP to the girders and rebuilding the Pier 18 bearing. Once all stabilization work has been finished, we will lower the work platforms onto barges. This will likely be in late November or early December.
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.
In the coming weeks, we will make the final determination as to whether we will move forward with repairing the current bridge or replacing it with a new structure. With our replacement consultant HNTB on board, we are ready to pivot to designing the demolition and replacement structure, should it be determined that it’s in the public’s best interest to replace rather than repair.
Over the past few weeks, we have:
- 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
- Poured concrete for the last grout pads to cement the post-tensioning brackets to the interior girder floor
- Received post-tensioning tendons
- Installed mounting hardware on the underside of the bridge girder to hold the post-tensioning brackets
Since SDOT closed the bridge in March, we have:
- Installed intelligent monitoring system to better understand what type of stabilization and repairs would be needed and to monitor the bridge during this work.
- Designed and started to install stabilization measures.
- Built and hoisted custom work platforms.
- Completed the first phase of carbon fiber wrapping.
- Started the cost-benefit analysis (CBA) that will help inform the decision to repair or replace the bridge.