The Dumbarton Bridge will be closed to all traffic – including pedestrian and bicycle traffic — over Memorial Day weekend for seismic refit work.
Caltrans will close the Dumbarton Bridge across San Francisco Bay from 10 p.m. Friday, May 25 to 5 a.m. Tuesday, May 29 for a seismic refit of the main channel crossing, which is the central portion of the bridge. A pedestrian & bicycle path on the south side of the bridge provides human-powered access for people traveling between the Peninsula and the East Bay.
A full bridge closure is necessary in order for crews to replace the existing expansion joint on the western side of the bridge with a state-of-the-art seismic joint that will absorb and dissipate energy during an earthquake. The joint spans across all lanes of traffic; therefore, there can be no motor vehicle, pedestrian, or bicycle traffic on the bridge during this operation.
Currently, the roadway on the bridge are steel and concrete boxes that sit on top of the columns supporting the bridge. During a major quake, these boxes can shift and shear the bolts connecting the road to the columns, causing bikes, cars, and people to plummet 85 feet to the Bay below.
Caltrans will jack the entire central span up five inches to install “friction pendulum bearings” on top of piers 17 through 30 this weekend. These devices absorb and dissipate the energy of a quake.
During this weekend’s closure, Caltrans suggests using the San Mateo to cross the Bay, but no bikes or pedestrians are allowed on that bridge. Cyclists can use the Bay Trail (where it exists) around the South Bay to the East Bay.
More at Dumbarton Bridge Info.