The Bay Bridge is the longest steel high-level bridge in the world. The Yerba Buena Tunnel with its diameter of 58 feet, which forms part of the highway between San Francisco and Oakland, is the tallest bore in the world. Additionally, the Bay Bridge can boast of the fact that its construction required the greatest expenditure of funds ever used for a single structure in the history of man. Its foundations extend to the greatest depth below water of any bridge built by man; one pier was sunk at 242 feet below water, and another at 200 feet. The deeper pier is bigger than the largest of the Pyramids and required more concrete than the Empire State Building in New York.
As finally constructed, the Bay Bridge is 43,500 feet or 8 1/4 miles long, from end to end of the approaches. The bridge proper, including the Yerba Buena crossing, is 23,000 feet or 4 1/2 miles long. On the San Francisco side of Yerba Buena Island, the structure consists of two complete suspension bridges with a central anchorage in the middle. The towers of the suspension rise 474 and 519 feet above water. Over the east channel, the span continues with one main cantilever span of 1,400 feet and, east of this, five truss spans each measuring 509 feet. The two cables supporting the suspensions are each 28 3/4 inches in diameter, and each contains 17,664 wires; the total length of these wires is 70,815 miles, which is enough to encircle the earth three times.
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