Transbay Tube

The Transbay Tube is a section of the BART transport system, which the San Francisco Bay underpasses between Oakland and San Francisco. The tube starts at the Embarcadero station in San Francisco and ends at the West Oakland station; the total length between the two stations 9 kilometers. The underwater length is 5.7 kilometers. Thus, the tube is the longest underwater crossing of a metro in the world. The deepest point is 41 meters.

With the construction of the tube was started in 1965, it was opened to traffic in 1974. The tube was manufactured according to the Senkkastenprinzip ashore from 57 individual segments. These segments were then taken using a barge in position, sunk and weighted with sand and gravel.