The Transbay Tube is a tunnel used by BART that runs under the San Francisco Bay in California and is the longest underwater tunnel for rapid transit in the world. The tube itself is 3.6 miles long and with approaches to the tube from the Embarcadero Station in San Francisco and the West Oakland Station in Oakland it totals 6 miles.

Construction

Construction was started in 1967 and the tube itself was finished in 1969. The tracks and electrification needed for the trains was finished in 1973 and it 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 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 placed over the tube. It cost approximately $180 million in 1970.

See also

• Bay Bridge
• Chunnel

External links

• BART's Transbay Tube (913KB PDF) - Detailed history of the tube and source of information for this article