San Francisco – Oakland Bay Bridge or simply Bay Bridge is a series of bridges in the San Francisco Bay Area , California . Part of Interstate 80 , the Bay Bridge immediately became the favorite way to travel between San Francisco and Oakland carrying more then 270,000 vehicles per day on its two decks. San Francisco – Oakland Bay Bridge has one of the longest spans in the world.
Designed by Charles H. Purcell , San Francisco – Oakland Bay Bridge construction started on July 9, 1933. The western span of the bridge between San Francisco and Yerba Buena Island presented an enormous engineering situation. The solution was to construct a massive concrete anchorage halfway between San Francisco and the island, and to build a complete suspension bridge on each side of the middle anchorage.
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 finally, the Transbay Terminal in San Francisco. The bridge consists of two major crossings connecting each shore with Yerba Buena Island, a natural outcropping located mid-bay. The Western crossing lies between Yerba Buena Island and San Francisco. It is composed of two complete suspension spans connected at a center anchorage
Bay Bridge was opened to traffic on November 12, 1936, six months before the Golden Gate Bridge , and was the largest and most expensive bridge of its time. It took three years and $77 million to build the original bridge and Transbay Terminal.
During the October 17, 1989, Loma Prieta earthquake, which measured 6.9 on the moment magnitude scale, a 50-foot (15 m) section of the upper deck collapsed indirectly causing one death . The bridge was closed for repairs and reopened on November 18 same year.
After being temporarily closed on October 27, 2009 due to failure of the recently repaired eastern span, the Bay Bridge reopened on November 2.
Yerba Buena Tunnel
Yerba Buena Tunnel is connecting the two halves of the bridge , measuring 76 feet (23 m) wide, 58 feet (18 m) high, and 540 feet (160 m) long. It is the largest diameter transportation bore tunnel in the world. The huge amount of rock and mud excavated was used in part to create Treasure Island in the Bay, next to Yerba Buena Island.
Bay Bridge Traffic
In its first year, San Francisco – Oakland Bay 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 in order to serve the purpose of carrying only vehicles.