Crews plan to replace a so-called "expansion joint," which allows the roadway to flex during an earthquake. The new seismic joint will include ball-bearing-like devices underneath the joint that will let the bridge deck shift like a pendulum rather than breaking. The bearings themselves will absorb and dissipate the seismic shocks.
With the new pendulum bearings, the roadway will sit 5 inches higher than it does now. The bridge deck currently stands 85 feet above the San Francisco Bay.
Over Memorial Day weekend, workers installed a similar joint at a pier on the western side of the bridge. This replacement will be on an eastern pier of the bridge.
Because the work will span all the lanes, no motor vehicles, pedestrians or bicycles will be allowed on the bridge during the weekend. About 61,000 vehicles cross the Dumbarton every day.
To get from the Peninsula to the East Bay, drivers can take Route 237 to the south or the San Mateo Bridge via Route 92 to the north.
The work is part of the San Francisco Bay Area Toll Bridge Seismic Retrofit Program, which includes six bridges, began in 2010 and is expected to be completed in 2013.
Information about current traffic conditions and driving times during the closure is available by calling 511 or going to www.511.org.
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