Transbay Tube - Conception and Construction

Conception and Construction

The idea of an underwater tube traversing San Francisco Bay was suggested by Emperor Norton, the eccentric "Emperor of these United States and Protector of Mexico" from San Francisco, in the mid-to-late 19th century. Serious consideration to the idea was first given in October 1920 by Major General George Washington Goethals, the builder of the Panama Canal. The alignment of Goethals's proposed tube is almost exactly the same as BART's Transbay Tube. In 1947, a joint Army-Navy Commission recommended an underwater tube as a means of relieving automobile congestion on the then ten-year old San Francisco – Oakland Bay Bridge.

Seismic studies commenced in 1959 and construction was started in 1965. The tube itself was finished in 1969. The tracks and electrification needed for the trains were finished in 1973 and the tube was opened to service in 1974. The tube is made of 57 individual sections that were built on land and towed out into the bay by a large barge. They were then positioned above where they were to sit and lowered into a trench packed with soft soil, mud and gravel for leveling along the bay's bottom. Once the sections were in place, bulkheads at each end of each of the sections were removed and a protective layer of sand and gravel was packed against the sides. It cost approximately $180 million in 1970.

During construction, the Transbay Tube was also used briefly as a shooting location for the end of George Lucas's film THX 1138. The final climb out to the daylight was actually filmed, with the camera rotated 90 degrees, in the incomplete (and decidedly horizontal) Transbay Tube before installation of the track supports, with Robert Duvall's character using exposed reinforcing bars as a ladder.

The western terminus of the tube directly connects to the downtown Market Street Subway near the Ferry Building, north of the Bay Bridge. The tube crosses under the bridge between the San Francisco Peninsula and Yerba Buena Island, and emerges in Oakland along 7th Street west of Interstate 880.