page_title: San Francisco–Oakland Bay Bridge
section_title: Construction
hierarchical_section_title: San Francisco–Oakland Bay Bridge / History / Construction
caption_attribution_description: English: Closeup view taken by the airship USS Akron of Yerba Buena Island to document progress of the construction of the San Francisco Oakland Bay Bridge. U.S. Navy photograph dates from mid July 1935. Deutsch: 1936: Die Bay Bridge im Bau.
context_page_description: The San Francisco–Oakland Bay Bridge, known locally as the Bay Bridge, is a complex of bridges spanning San Francisco Bay in California. As part of Interstate 80 and the direct road between San Francisco and Oakland, it carries about 260,000 vehicles a day on its two decks. It has one of the longest spans in the United States.
  The toll bridge was conceived as early as the California Gold Rush days, but construction did not begin until 1933. Designed by Charles H. Purcell, and built by American Bridge Company, it opened on Thursday, November 12, 1936, six months before the Golden Gate Bridge. It originally carried automobile traffic on its upper deck, with trucks, cars, buses and commuter trains on the lower, but after the Key System abandoned rail service, the lower deck was converted to all-road traffic as well. In 1986, the bridge was unofficially dedicated to James Rolph.
  The bridge has two sections of roughly equal length; the older western section, officially known as the Willie L. Brown Jr. Bridge, connects downtown San Francisco to Yerba Buena Island, and the newer unnamed eastern section connects the island to Oakland.
context_section_description: Before work got underway, 12 massive underwater telephone cables were moved 1,000 feet north of the proposed bridge route by crews of the Pacific Telephone and Telegraph Co. during the summer of 1931.
  Construction began on July 9, 1933.  Ultimately, twenty-four men would die constructing the bridge.
  The western section of the bridge between San Francisco and Yerba Buena Island presented an enormous engineering challenge. The bay was up to 100 feet (30 m) deep in places and the soil required new foundation-laying techniques. A single main suspension span some 4,100 feet (1.2 km) in length was considered but rejected, as it would have required too much fill and reduced wharfage space at San Francisco, had less vertical clearance for shipping, and cost more than the design ultimately adopted. The solution was to construct a massive concrete anchorage halfway between San Francisco and the island, and to build a main suspension span on each side of this central anchorage.
  East of Yerba Buena Island, the bay to Oakland was spanned by a 10,176-foot (3.102 km) combination of double cantilever, five long-span through-trusses, and a truss causeway, forming the longest bridge of its kind at the time. The cantilever section was longest in the nation and third-longest anywhere.
  Much of the original eastern section was founded upon treated wood pilings. Because of the very deep mud on the bay bottom it was not practical to reach bedrock, although the lower levels of the mud are quite firm. Long wooden pilings were crafted from entire old-growth Douglas fir trees, which were driven through the soft mud to the firmer bottom layers.
caption: The Bay Bridge under construction at Yerba Buena Island in 1935
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