West Approach

 

Seismic safety retrofit work on the West Approach — bordered by 5th Street and the Anchorage at Beale Street — involves completely removing and replacing this one-mile stretch of Interstate 80 and six on- and off-ramps in its original footprint. This work occurs while more than 280,000 vehicles flow daily in the midst of this essential construction.
 
The West Approach originally had one foundation system supporting both an upper and lower deck configuration from 3rd Street to Beale Street. Each deck now has its own independent column and foundation support system, a crucial aspect of making the West Approach seismically sound. The roadways between 3rd and 5th Streets are parallel concrete decks that transition into the double-deck configuration as drivers approach the West Span of the Bay Bridge.
 
Work on the 72-year-old structure began in 2003, and is scheduled for completion in early 2009. Remaining work includes demolishing the temporary eastbound structure, and the reopening of the Harrison Street on- and off-ramps. To keep traffic flowing, and to enable work to occur in a densely populated residential and commercial hub south of Market Street, builders are performing a “retrofit by replacement,” one of the most complex projects in Caltrans history.
 
To minimize disruptions to the neighborhood, and to keep the bridge’s traffic moving, the project was performed in a series of six elaborate stages, including a series of lane shifts, regular lane and ramp closures, and one partial bridge closure.
 
Each of the six stages of retrofit work follows a carefully staged formula to meet seismic safety standards. A temporary structure is built and vehicles are rerouted to it. The old structure is then demolished, and work begins on the new structure in the original footprint. Drivers are then rerouted back onto the completed replacement structure, and the temporary structure is demolished.
 
The opening of the permanent eastbound lanes in April 2008 is the project’s latest milestone. For more than a year eastbound motorists were diverted onto a temporary structure tucked beneath westbound traffic coming off the Bay Bridge. Those eastbound motorists now have unobstructed views for most of the way to the Bay Bridge. The opening of the permanent structure carrying eastbound traffic was the final major traffic shift — from a temporary structure to a permanent one — for the West Approach.

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