12:01 PM: SDOT says its stabilization contractor Kraemer North America has reached another milestone. SDOT spokesperson Ethan Bergerson tells WSB, “We have completed the Pier 18 release work as planned.” SDOT detailed the Pier 18 bearing problem in April: “We discovered that one particular joint has become stuck, which appears to be magnifying the daily stresses on the bridge. Specifically, the issue is with the lateral bearings at the top of the Pier 18 support columns. This isn’t the sole cause of cracking on the bridge, but our bridge experts think it is a major part of the problem.” The bearings are pieces of rubber that “manage movement” as the bridge handles traffic and other stresses. The release is just part of the stabilization work – other parts involve strengthening the damaged section of the bridge – but it’s definitely a milestone. SDOT promises more details later today on what the Pier 18 release means and what’s next. We’ll add that information when it’s in.
2:12 PM: SDOT’s full announcement is now out, including:
… SDOT bridge engineers worked with the contractor to determine the best way to “release” the bearings so they are no longer compressed.
This involved building a temporary platform to perform the work. Then, specialized equipment was used to precision-demolish the concrete surrounding the bearings. Over the next couple of weeks, we will place the new bearings, and then pour the new concrete to hold them in place, setting the stage for future repair or replacement of the bridge.
The bearing release is part of a series of vital steps we’ve taken to stabilize the bridge since it closed in March. Within weeks of closing the West Seattle High-Rise Bridge, SDOT has had crews on top, underneath, and inside the bridge working six days a week to stabilize the center span, make it stronger and keep options open.
As the important discussion about repairing or replacing the bridge continues, crews are continuing to focus on measures that need to occur regardless of whether the bridge will be repaired now or if we will pivot immediately to replacement. This includes carbon fiber wrapping and installation of a post-tensioning system, both of which will wrap up later this month.
As colder temperatures and increased moisture can cause bridge elements to expand and contract, SDOT will continue to monitor the bridge with the intelligent monitoring system installed in May.