San Francisco-Oakland Bay Bridge is one of the longest bridges in the world over navigable water. It crosses San Francisco Bay between Oakland and San Francisco, California. The Bay Bridge is really a series of bridges. It is more than 8 miles (13 kilometers) long, including its two approaches. It carries two decks for traffic. Opened in 1936, it cost about $77 million.
One part of the Bay Bridge, consisting of two suspension bridges, reaches from San Francisco to Yerba Buena Island in the bay. The roadway passes through a double-deck, 1,790-foot (546-meter) tunnel. From this tunnel, the bridge crosses to Oakland and Berkeley.
Halfway between San Francisco and Yerba Buena, the suspension spans are anchored to a concrete anchorage pier. The spans themselves are carried by suspension cables supported by towers extending more than 500 feet (150 meters) above the water. The two center spans on each side of the anchorage pier are 2,310 feet (704 meters) long. In October 1989, an earthquake caused part of the bridge to collapse. The bridge was repaired, and it was reopened in November.
