San Francisco-Oakland Bay Bridge

Photo by Cliff West

Built from July 9, 1933 to November 12, 1936, the double-deck connection of Interstate 80 between Oakland and San Francisco is actually two separate bridges. The 9,260-foot West Span (pictured) is two suspension bridges connected end-to-end at a man-made anchor point. The towers of the West Span are 526 feet tall, and the bridge has 220 feet of vertical clearance above the bay. The 10,176-foot East Span (not pictured) is a combination of cantilever beams and trusses. The two spans meet at Yerba Buena Island, where they are connected by a 1,700-foot tunnel. The tunnel, at 76 feet wide and 56 feet high, is the largest-diameter bore in the world. On average, 280,000 vehicles make this crossing every day.

On October 17, 1989, the Loma Prieta earthquake caused a 50-foot section of the upper deck of the East Span to collapse onto the lower deck. The bridge was closed for a month for repairs. Today, a new East Span has been built.

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