10:12 AM: As of early this morning, a second work platform is in place under the four-months-closed West Seattle Bridge. The first one went up a week ago; in a meeting Thursday, SDOT managers mentioned another one was set to be moved into place today, so we went out to check. It’s east of the first one, and it’s for crews with stabilization contractor Kraemer North America. As explained by SOOT here, “The platforms will allow the team to safely access the exterior of the bridge girders to work on measures intended to slow cracking – this includes wrapping sections with carbon fiber-reinforced polymer (and) adding external post-tensioning tendons, and releasing the bearings at Pier 18.”

4:55 PM: SDOT points out in its announcement of today’s installation, the “two” platforms are actually four. Here’s how they’ll be used:

The work platforms will be under the bridge for at least 3 months while we do repair work, and then crews will repeat the same process to gently lower them down to barges waiting to receive them below.

SDOT is now entering the next phase of stabilization work. Over the next few months, crews will use the work platforms for bridge access to perform stabilization measures including:

First, we will inject epoxy to seal the cracks in order to protect the bridge’s skeleton of steal post-tensioning cables holding up the concrete.

We will wrap sensitive sections of the bridge with carbon fiber reinforced polymer to strengthen the bridge much like putting a cast on a broken bone.

Then we will install additional steel post-tensioning cables inside the hollow portion of the bridge to help hold up the bridge, like adding braces for extra support.

Next, we will repair the locked bearings at Pier 18 which are preventing the bridge from reacting to normal daily stresses as intended.

Finally, we will go back and install additional carbon fiber wrapping and post-tensioning cables for further strengthening and support.