San Francisco Bay Bridge: Construction, History & Facts

Instructor: Summer Stewart

Summer has taught creative writing and sciences at the college level. She holds an MFA in Creative writing and a B.A.S. in English and Nutrition

The San Francisco Bay Bridge in California is a stunning example of a well-built bridge in the United States. In this lesson, we will learn about its history, construction and many facts.

Background on the Bridge

San Francisco Bay Bridge
SF Bridge

Did you know that the lower deck of the San Francisco Bay Bridge was used for trains and semi-trucks until 1962? Cars didn't begin driving on the lower deck of the bridge until the railroad company that used the bridge shut down.

The San Francisco Bay Bridge connects San Francisco to Oakland using a west and east span, which converge on Yerba Buena Island. The bridge is critical in cutting down commuting times, and it has also been subject to several renovations since its opening day.

History of the Bridge

The San Francisco Bay Bridge was opened to the public on November 12, 1936, three years after construction began in 1933. However, the idea of a bridge spanning the bay came to light as early as the California Gold Rush.

At the beginning, the upper deck of the double-decker bridge was used for vehicles, while the lower deck was reserved for trains and semi-trucks until 1962. The switch from trains to automobiles occurred because the rails were not being used as often as before. Ultimately, the bridge was refitted to accommodate trucks and cars on both levels.

The bridge has suffered several tragedies. In 1989, the Loma Prieta Earthquake that shook the entire region busted out the bolts in a section of the upper deck on the east span, which caused an upper deck segment to fall onto the lower deck. The damage killed one person and shut the bridge down for nearly a month.

The bridge became subject to more reconstruction after the 1994 Northridge Earthquake. Since the eastern span was more likely to be damaged by an earthquake, the state decided to replace the entire east span with a new single-layer span. It took over five years to approve the new construction. The east span construction began in 2004 and finished in 2013. The new span is a suspension bridge, while the old span was a cantilever bridge. According to the state of California, the new bridge can withstand an earthquake up to a magnitude of 8.5.

As of 2016, the western span of the San Francisco Bay Bridge is lit up with 25,000 LED lights. The light show began as a temporary event to celebrate the bridge's 75th anniversary, but the city made it permanent because it proved to increase the economy by over $100 million each year.

Construction of the Bridge

The construction of the San Francisco Bay Bridge began in 1933 and finished way ahead of schedule. The bridge was planned by Charles H. Purcell, engineered by Ralph Modjeski, and built by the American Bridge Company.

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