The Seattle Department of Transportation provided an inside look at the repairs, and updates made to the West Seattle Bridge on Aug. 25, ahead of it's re-opening on Sept. 18 after 909 days of closure.

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It's likely to open without fanfare in the early morning hours of Sept. 18 as promised SDOT said.

On hand to talk about the work done were bridge Program Director Heather Marx and contracted engineer from WSP Greg Banks.

The press conference was frequently interrupted by construction sounds inside the girders as workers carried on the effort to complete the repairs.

Marx spoke about the natural cracks that appear in concrete that are noted and marked and monitored. She said that the normal 2 year federal standard for inspections would be more frequent initially as the bridge returns to service then slow down over time as conditions warrant.

Bridge repairs included three key procedures: epoxy injections to fill cracks, carbon-fiber wrapping to add strength, and post-tensioning with steel cables to compress the concrete.

An intelligent monitoring system inside the bridge made up of hundreds of movement sensors, cameras, and other instruments is now in place. This system can detect subtle movements or any growth of existing cracks. It monitors the bridge 24/7 and provides real-time details and alerts to staff who oversee the performance of bridge repairs. Permanent inspection platforms are now installed inside the bridge so that inspectors can regularly examine the bridge’s structural components in the years to come.

The most important part of the repair effort has been completing a new steel post-tensioning system inside the bridge. Nearly 10 miles of new steel cables were installed during the first phase of emergency repairs and nearly 50 more miles of steel cables during the final phase. Each of the cables is anchored and supported by specialized concrete blocks woven into the bridge and capable of holding more than 20 million pounds of force.

The new post-tensioning system works in tandem with other repairs to the bridge, including an extensive network of reinforced carbon fiber sheets wrapped inside and outside the bridge walls like a cast on a broken bone. Crews have also extensively injected epoxy into cracksto prevent further deterioration or corrosion and fuse the cracked concrete. 

The work remaining includes:

• Complete final epoxy injections and carbon-fiber wrapping
• Complete cure time for the carbon-fiber wrapping
• Remove work platforms
• Load test and inspect the repairs
• Restore the pavement on the bridge deck
• Remove construction equipment and get the bridge ready for the public

Some of the load testing will involve the use of 12 80 ton trucks that will traverse the bridge.