The present bridge was preceded by an earlier structure, which in turn replaced a ferry. The ferry service was started in 1917 by two businessmen, Aven Hanford from Vallejo and Oscar Klatt from San Francisco. Demand grew so fast (in 1922 the ferry carried 400,000 automobiles) that in 1925 Hanford and Klatt commenced the building of a bridge, employing U.C. Berkeley engineering professor Charles Derleth, Jr. as Chief Engineer. Bridging the strong tidal current took 25 months and on May 21, 1927 the Carquinez Bridge opened for traffic (just hours after Charles Lindbergh spanned the Atlantic by solo flight). The bridge was funded by tolls.
In 1940 the state of California took over and gradually reduced the tolls until crossing was free. With traffic greatly increasing, it was decided in 1955 to build a twin parallel bridge, 200 feet east of the existing structure.
The new bridge was designed to match the original Carquinez Bridge and opened on November 25, 1958 incorporating many new features made possible by engineering advances since the 1920s. These included the use of welded steel fabrication for the cantilever spans, and T-1 steel, three times stronger than the usual steel used in bridge construction. Nevertheless, it is currently under a major retrofit. The bridge is 0.8 miles long with a tower height of 314 feet and a vertical clearance of 148 feet.
Many of the components of the 1927 bridge, now more than 70 years old, are deteriorating and difficult to maintain. Because a major retrofit would be virtually impossible without closing the bridge to traffic, it will be replaced by a two-pier suspension bridge due for completion by 2003.
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