Sunday, May 29, 2011

California's Bridges: East Bay Bridges across San Francisco Bay (2)

June 2004 (37.818 deg., -122.344 deg.) East Bay Bridges

After the 1989 Loma Prieta earthquake, it was decided to retrofit the existing East Bay Bridge. However, it was difficult to achieve the performance requirements and so it was thought a new bridge might make a more economical alternative.

A cofferdam was build in the Bay for each bridge pier. Then a special rig was set up to drive the steel piles at a batter through hundreds of feet of Bay Mud. Once all the piles were driven, the reinforcement for the pile cap and pier could be placed. It's incredible that a separate crane was used for each pier. They built the eastbound piers first and then they turned the cranes around to build the westbound piers. After the skyway was built, they started working on the signature suspension span and the approach structures.

Since we are spending some time in San Francisco Bay, I thought I might provide a map to show the location of the toll bridges. For some reason, the Benecia-Martinez Bridge (east of the Carquinez Bridge) isn't on my map. 

So far we've looked at the East Bay, Richmond-San Rafael, and the Carquinez Bridges. The map shows the 'Bay Bridge' which is made up of a double suspension bridge to the west, a tunnel at Yerba Buena Island, and the East Bay Bridge which is currently being replaced. All of these toll bridges got a retrofit and many have older and newer bridges side by side.
Creative Commons License
California's Bridges: East Bay Bridges across San Francisco Bay (2) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.

No comments: