BART's Link under the San Francisco Bay: The Transbay Tube
BAY AREA RAPID TRANSIT DISTRICT
TRANS-BAY TUBE
Dedicated to the people of Alameda, Contra Costa and San Francisco Counties for their vision and foresight.
September 19th, 1969
TRANS-BAY TUBE
Dedicated to the people of Alameda, Contra Costa and San Francisco Counties for their vision and foresight.
September 19th, 1969
Please note this page is still “under construction” but feel free to browse around for fun. 2/1/26
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One of the most ambitious engineering projects in history
was the Transbay Tube, the critical link between San Francisco and the East Bay.
When built, the 3.6-mile-long Transbay Tube was the deepest and longest underwater
vehicular tube tunnel in the world and costed $180 million – almost 14% of the
entire system’s capital construction cost.
The tube consists of 57 binocular-shaped steel and concrete sections that were individually lowered and connected in a specially built trench on the floor of the San Francisco Bay. The sections themselves, 12,000 ton displacement and ranging from 273 to 336 feet long, were fabricated at Bethlehem Shipyard in San Francisco and lowered onto the Bay floor using special laser surveying instruments and connected to adjacent sections. The tube’s designers, Parsons, Brinkerhoff, Quade and Douglas designed the tube to absorb earthquake shocks by placing the tube in soft soil, gravel, and mud alongside connecting the tube to its terminal buildings via flexible connections. The tube was also designed in the face of significant environmental challenges - fast running water, 80-130 feet depth, two horizontal curves, and 6 vertical curves. |
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A joint venture of four large contracts: Peter Kiewit Sons
Co.; Raymond International, Inc.; Tidewater Construction Corp.; and
Healy-Tibbitts Construction Co. formed the Trans-Bay Constructors and built the
Tube and ventilation structures. The first section lowered into place and the last section was lowered into place
in April 1969 and formally dedicated in September 1969. Construction then
turned towards installation of track, train control, and ventilation equipment
which was completed by early 1973.
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What a section of the tube looks like, in 1:300 scale
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Building the Tube
A walk under the water: The Bay Area Underwater Rapid Transit Tube (1969)
The Tube in Operation
With the public preview of the Powell Street station on June 10, 1972, the first train was moved through the tube, towed by a highrailer and took all day.
The first BART test train to run on its own power, in ATO, under the San Francisco Bay, occurred on August 10, 1973. Train 222, consisting of cars 212-513-117, departed Oakland West at 8:38 am, arriving at Montgomery Street at 8:44 am, at PL2, 70 mph. For the return trip, the train departed Montgomery at 9:14, running in manual until M17 interlocking, then resumed ATO at PL1, 80 mph to Oakland West, arriving at 9:20 am. Noting a historical coincidence, BART car 117 was among the first of the BART fleet to cross the Bay, Key System car 117 was the first Key unit to cross the bridge. Train Attendants for the run were Dennis Mattos and Clifford Quon. BART also unknowingly carried its first transbay commuter, Al Hart, a staff announcer with an SF radio station, hooked a ride from Oakland West to Montgomery and walked the few blocks to work. He described the ride as “absolutely fantastic” and “flawless in every respect.”
The first BART test train to run on its own power, in ATO, under the San Francisco Bay, occurred on August 10, 1973. Train 222, consisting of cars 212-513-117, departed Oakland West at 8:38 am, arriving at Montgomery Street at 8:44 am, at PL2, 70 mph. For the return trip, the train departed Montgomery at 9:14, running in manual until M17 interlocking, then resumed ATO at PL1, 80 mph to Oakland West, arriving at 9:20 am. Noting a historical coincidence, BART car 117 was among the first of the BART fleet to cross the Bay, Key System car 117 was the first Key unit to cross the bridge. Train Attendants for the run were Dennis Mattos and Clifford Quon. BART also unknowingly carried its first transbay commuter, Al Hart, a staff announcer with an SF radio station, hooked a ride from Oakland West to Montgomery and walked the few blocks to work. He described the ride as “absolutely fantastic” and “flawless in every respect.”
Testing continued for over a year.
Requirements for revenue service
included: timely delivery of acceptable cars, proof of the adequacy of the SORS
train protection system, and improvement in equipment systems reliability.
The first test, a safety demonstration for CPUC on August 3, 1974, Full scale 36-train test to demonstrate system performance as part of the process to obtain CPUC approval to begin transbay service. And therefore limited to official observers. The second test on September 7th invited members of the press and families to ride the system as a preview. Five stations were open to passengers – All four terminal station and Lake Merritt, but trains ran system wide. The CPUC concluded that the BART system was “as safe as it can be” as did the Lawrence Laboratories of Berkeley, having concluded that BART’s technology was “free of serious problems”. The CPUC approved BART transbay service on August 28th and service began in earnest.
The first test, a safety demonstration for CPUC on August 3, 1974, Full scale 36-train test to demonstrate system performance as part of the process to obtain CPUC approval to begin transbay service. And therefore limited to official observers. The second test on September 7th invited members of the press and families to ride the system as a preview. Five stations were open to passengers – All four terminal station and Lake Merritt, but trains ran system wide. The CPUC concluded that the BART system was “as safe as it can be” as did the Lawrence Laboratories of Berkeley, having concluded that BART’s technology was “free of serious problems”. The CPUC approved BART transbay service on August 28th and service began in earnest.
