Transbay Tube
Encyclopedia
The Transbay Tube is the part of BART
which runs under San Francisco Bay
in California
. The tube is 3.6 miles (5.7 km) long; including approaches from the nearest stations (one of which is underground), it totals 6 miles (9 km). It has a maximum depth of 135 feet (41 m) below the surface.
The tube was constructed on land, transported to the site then submerged and fastened to the bottom (mostly by packing the sides with sand and gravel). This immersed tube
technique is in contrast to bored tunneling, where rock is removed to leave a passage.
, 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, bulkhead
s 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.
As a precaution, the tube was shut down along with the rest of the BART lines following significant earthquake
s. The largest to date was the 1989 Loma Prieta earthquake
, but the tube was found to be safe and reopened just six hours later. Many area highways were damaged, and the Bay Bridge was unusable, so BART ridership reached very high levels.
and the planned California High Speed Rail system. The four-bore tunnel would provide two tunnels for BART and two tunnels for conventional/high-speed rail. In the terminal there would be 6 tubes: 4 for HSR and 2 for Caltrain.
Bay Area Rapid Transit
Bay Area Rapid Transit is a rapid transit system serving the San Francisco Bay Area. The heavy-rail public transit and subway system connects San Francisco with cities in the East Bay and suburbs in northern San Mateo County. BART operates five lines on of track with 44 stations in four counties...
which runs under San Francisco Bay
San Francisco Bay
San Francisco Bay is a shallow, productive estuary through which water draining from approximately forty percent of California, flowing in the Sacramento and San Joaquin rivers from the Sierra Nevada mountains, enters the Pacific Ocean...
in California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
. The tube is 3.6 miles (5.7 km) long; including approaches from the nearest stations (one of which is underground), it totals 6 miles (9 km). It has a maximum depth of 135 feet (41 m) below the surface.
The tube was constructed on land, transported to the site then submerged and fastened to the bottom (mostly by packing the sides with sand and gravel). This immersed tube
Immersed tube
An immersed tube is a kind of underwater tunnel composed of segments, constructed elsewhere and floated to the tunnel site to be sunk into place and then linked together. They are commonly used for road and rail crossings of rivers, estuaries and sea channels/harbours...
technique is in contrast to bored tunneling, where rock is removed to leave a passage.
Conception and construction
The idea of an underwater tube traversing San Francisco Bay was suggested by Emperor Norton, the eccentric "Emperor of North America" 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 GoethalsGeorge Washington Goethals
George Washington Goethals was a United States Army officer and civil engineer, best known for his supervision of construction and the opening of the Panama Canal...
, 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
Electrification
Electrification originally referred to the build out of the electrical generating and distribution systems which occurred in the United States, England and other countries from the mid 1880's until around 1940 and is in progress in developing countries. This also included the change over from line...
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
Barge
A barge is a flat-bottomed boat, built mainly for river and canal transport of heavy goods. Some barges are not self-propelled and need to be towed by tugboats or pushed by towboats...
. They were then positioned above where they were to sit and lowered into a trench
Trench
A trench is a type of excavation or depression in the ground. Trenches are generally defined by being deeper than they are wide , and by being narrow compared to their length ....
packed with soft soil, mud and gravel for leveling along the bay's bottom. Once the sections were in place, bulkhead
Bulkhead
Bulkhead may refer to:* Bulkhead, a compartment of a building for preventing spread of fires, see Compartmentalization * Bulkhead , a retaining wall used as a form of coastal management, akin to a seawall, or as a structural device such as a bulkhead partition* Bulkhead , a wall within the hull of...
s 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
George Lucas
George Walton Lucas, Jr. is an American film producer, screenwriter, and director, and entrepreneur. He is the founder, chairman and chief executive of Lucasfilm. He is best known as the creator of the space opera franchise Star Wars and the archaeologist-adventurer character Indiana Jones...
's film THX 1138
THX 1138
THX 1138 is a 1971 science fiction film directed by George Lucas in his directorial debut. The film is based on a screenplay by Lucas and Walter Murch...
. 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
Robert Duvall
Robert Selden Duvall is an American actor and director. He has won an Academy Award, two Emmy Awards, four Golden Globe Awards and a BAFTA over the course of his career....
'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
Ferry Building
The San Francisco Ferry Building is a terminal for ferries that travel across the San Francisco Bay and a shopping center located on The Embarcadero in San Francisco, California. On top of the building is a large clock tower, which can be seen from Market Street, a main thoroughfare of the city...
, north of the Bay Bridge. The tube crosses under the bridge between the San Francisco Peninsula
San Francisco Peninsula
The San Francisco Peninsula is a peninsula in the San Francisco Bay Area that separates the San Francisco Bay from the Pacific Ocean. On its northern tip is the City and County of San Francisco. Its southern base is in Santa Clara County, including the cities of Palo Alto, Los Altos, and Mountain...
and Yerba Buena Island
Yerba Buena Island
Yerba Buena Island sits in the San Francisco Bay between San Francisco and Oakland, California. The Yerba Buena Tunnel runs through its center and connects the western and eastern spans of the San Francisco-Oakland Bay Bridge. It has had several other names over the decades: Sea Bird Island, Wood...
, and emerges in Oakland
Oakland, California
Oakland is a major West Coast port city on San Francisco Bay in the U.S. state of California. It is the eighth-largest city in the state with a 2010 population of 390,724...
along 7th Street west of Interstate 880.
Incidents
In January 1979, an electrical fire occurred on a train as it was passing through the tube. One firefighter (Lt. William Elliott, 50, of the Oakland Fire Department) was killed in the effort to extinguish the blaze. Since then, safety regulations have been updated.As a precaution, the tube was shut down along with the rest of the BART lines following significant earthquake
Earthquake
An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...
s. The largest to date was the 1989 Loma Prieta earthquake
Loma Prieta earthquake
The Loma Prieta earthquake, also known as the Quake of '89 and the World Series Earthquake, was a major earthquake that struck the San Francisco Bay Area of California on October 17, 1989, at 5:04 p.m. local time...
, but the tube was found to be safe and reopened just six hours later. Many area highways were damaged, and the Bay Bridge was unusable, so BART ridership reached very high levels.
Future
As BART celebrated the 50th anniversary of its creation in 2007, it announced its plans for the next 50 years. Its vision includes a four-bore transbay tube beneath San Francisco Bay that would run parallel and south of the existing tunnel and emerge at the Transbay Transit Terminal to provide connecting service to CaltrainCaltrain
Caltrain is a California commuter rail line on the San Francisco Peninsula and in the Santa Clara Valley in the United States. The northern terminus of the rail line is in San Francisco, at 4th and King streets; its southern terminus is in Gilroy...
and the planned California High Speed Rail system. The four-bore tunnel would provide two tunnels for BART and two tunnels for conventional/high-speed rail. In the terminal there would be 6 tubes: 4 for HSR and 2 for Caltrain.
See also
- Key SystemKey SystemThe Key System was a privately owned company which provided mass transit in the cities of Oakland, Berkeley, Alameda, Emeryville, Piedmont, San Leandro, Richmond, Albany and El Cerrito in the eastern San Francisco Bay Area from 1903 until 1960, when the system was sold to a newly formed public...
- San Francisco – Oakland Bay Bridge
External links
- BART History
- BART History and Photos
- ASME National Historic Mechanical Engineering Landmark PDF - history and concept photos