For months, some 82,000 drivers and 30,000 transit riders a day have felt an extra jolt at the south end of the Aurora Bridge, where a raised steel plate covers the site of a crumbling expansion joint.
Now, the Washington State Department of Transportation says it’s in the final stretch of repairing what spokeswoman Jamie Holter calls the “ski jumps,” formally known as the S6 joint, near the Canlis restaurant. Expansion joints are gaps between the spans of a bridge, in this case about 2 inches wide, that allow the whole crossing to thermally expand or contract without cracking. The job should be done by early 2013 — later than an earlier DOT prediction of October.
The job is complicated by corrosion in a major, weight-bearing steel beam, shown here.
This beam will be replaced Wednesday and Thursday. Four concrete pours will follow, along with installation of the steel expansion joints across the bridge deck. There will be an overnight closure of two northbound lanes Sunday night, and other short-term closures in the second half of December. The last concrete pour there is expected January 4, with the job done by Jan. 10, Holter said.
Meanwhile, the DOT is looking for a way to reduce the “ke-bonk, ke-bonk” noise in spots where the traffic forces bang steel parts against each other below the deck, Holter said. Because the bridge is 80 years old, repairing it requires non-standard parts and strategies. The joint repairs are one phase of a broader $6 million seismic strengthening project. “It’s functionally obsolete, it may even be structurally obsolete, but it’s not going to fall down,” Holter said. Construction updates are linked here.