Bay Bridge History
The Original Bay Bridge
In 1936, the East and West communities of the Bay Area came together like never before. While ferries had long carried people across the Bay's often choppy waters, automobiles were the future of transportation. This meant local residents wanted a quick way to drive between the rapidly growing cities of San Francisco and Oakland. As expected, as soon as the San Francisco-Oakland Bay Bridge was built in 1936, it immediately became the favorite way to travel between San Francisco and the East Bay.
Cynics believed that the bridge would be impossible to build due to the potential impact of turbulent waters and gusty winds. Engineers had assumed that the area's high winds posed a greater threat than earthquakes, despite the bridge's proximity to two major fault lines. The varying soils and water depths, the inaccessibility to bedrock, and the unique design challenges inherent in developing a bridge to span eight miles across the Bay led some to believe that building such a bridge was unthinkable.
The largest and most expensive bridge of its time, the Bay Bridge faced not just natural obstacles, but political hurdles as well. There had been discussion of building a bridge between San Francisco and Oakland since the 1870s, but construction did not move forward until the Reconstruction Finance Corporation, with support from President Herbert Hoover, agreed to purchase bonds to be repaid later with bridge tolls.
Listen to the 1936 radio broadcast of the opening event.
The bridge design needed to break the mold. The result was a unique bridge that combined the best elements of several different designs. While a suspension bridge was appropriate for spanning the deep waters near San Francisco, it was not practical for spanning the shallow mudflats near Oakland. Nor was it feasible to build a suspension bridge to span the entire distance between the two cities. The West Span, comprised of two suspension bridges, allowed easy passage for the Navy and merchant ships sailing to and from San Francisco.
Connecting Yerba Buena Island (YBI) and Oakland's shore, the original East Span features a truss-cantilever design, with pilings reaching hundreds of feet under the Bay to anchor the bridge. Connecting the East and West Spans at YBI is the world's largest-diameter bore tunnel, at 76-feet-wide and as tall as a four-story building. At the time, the West Span's center anchorage was taller than any building in San Francisco.
The bridge was constructed in five phases: first the East Span, followed by the tunnel through Yerba Buena Island, and then the West span. This was followed by the I-80 West Approach and on- and off-ramps, and finally, the Transbay Terminal in San Francisco. The terminal housed the control center for the four railroad lines along the bridge's lower deck. It took three years – and $77 million – to build the original bridge and Transbay Terminal.
In its first year, the bridge served nine million vehicles, far exceeding expectations. By 1950, it was serving 29 million vehicles. By 1958, the bridge's lower deck was reconfigured to cease carrying trains, and was transformed into its current configuration, with both upper and lower decks open only to vehicular traffic.
Following the Loma Prieta Earthquake, which caused major damage on a section of the East Span, the Bay Bridge is once again in the midst of a major transformation. The seismic retrofit, which will ultimately reinforce and rebuild each section of the bridge, is perhaps no less ambitious than building the original bridge.
- Bay Bridge construction began July 9, 1933
- The bridge opened November 12, 1936
- Until 1962 cars drove in both directions on the upper deck, while trucks and trains travelled in both directions on the lower deck
- The bridge carried 9 million vehicles in its first year (102,200,000 per year today)
- The cost of the original bridge was $77 million in 1936 (included Transbay Transit Terminal)
- Key System trains operated on the bridge from 1938 to 1958
- In 1962 the bridge was reconfigured to carry cars and trucks only
- The East Span suffered a partial collapse in the 1989 Loma Prieta earthquake
- The Bay Bridge was the longest bridge in the world when it was built
- The center West Span anchorage was larger than any building in San Francisco at the time
- Opening celebrations around the area lasted four days