Thursday, December 6, 2012

San Francisco Bay Bridge: Under Construction

Source: Caltrans

Self-Anchored Suspension Span (SAS)
This new part of the Bay Bridge, spanning over a deep water channel on the east side of Yerba Buena Island, is now self-supporting.
(Excerpt) "The weight of the bridge is currently supported by the single, nearly 1-mile long main cable. Workers successfully completed the highly complex process called load transfer, which shifted the bridge’s weight from the temporary supports to the main cable; the process took just under three months. The SAS, at 2,047 feet, is the world’s longest SAS and the signature element of the new East Span."
 During load transfer, the 200 suspender ropes (vertical cables connecting the single main cable to the road decks) by design pulled the main cable 16 feet down and 30 feet out. Also by design, the roadway lifted approximately 1.5 feet. It no longer bears on the temporary and removable steel supports below.

Bay Bridge Sections
The entire bridge from San Francisco to Oakland can identified with six main sections:
West Approach
West Span
Yerba Buena Island Transition
Self-Anchored Suspension Span (SAS)
Oakland Touchdown
Source: The San Francisco - Oakland Bay Bridge Seismic Safety Projects

The above linked website is rich in content about the new Bay Bridge construction and retrofitting projects within each of these main sections. Some of the sections are already in use. Some areas have been in continuous use throughout construction. This very significant public infrastructure project started in 2002, will include some changes in most of the Bay Bridge, will total approximately 7 billion dollars, and is currently on-schedule for completion in 2013.

On Topic:
San Francisco's Treasure Island Plan
Bay Area Treasure Island Redevelopment

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