How did they build the BART underwater?

This tunnel under San Francisco Bay carries commuters on the subway between Oakland and San Francisco, and is one of the longest immersed tunnels in the world. Immersed tunnels are constructed using pre-made tubes that are floated to the location and sunk into place. The segments are then attached under water.



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In the case of the San Francisco-Oakland BART tunnel, it was constructed on shore in pieces and then floated out to their respective locations on the bay and “sunk” into place on top of a pre-dug trench. Each section is then connected together to form an airtight chamber.

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Constructed in 57 sections, and reposing on the bay floor as deep as 135 feet beneath the surface, the remarkable $180 million structure took six years of toil and seismic studies to design, and less than three years to contract.

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Earthquake Safety Program The Transbay Tube is BART's most critical asset. Although the tube is structurally sound, in a very large and very rare earthquake, the outer shell and concrete liner are predicted to crack.

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Seats are scrubbed with hot water and disinfectant soap during a thorough clean. BART recently increased the frequency of thorough cleans from every 900 hours of train car service to every 450 hours, meaning we've doubled the number of times the cars in our system undergo a deep clean.

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Like most trains, BART wheels are tied together with rigid axels and no differentials. This means the wheels always rotate at the same speed, even around corners. Because the inner radius is smaller, there is less distance to travel, which can cause a slippage between the wheels and track, which is noisy.

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BART (Bay Area Rapid Transit) is a modern rapid rail system (30 km underground in downtown San Francisco Oakland and Berkeley) which crosses the Bay in a 5.8 km long immersed-tube tunnel and serves surrounding cities like Berkeley, Oakland and Richmond in the counties of Alameda, Contra Costa, San Francisco and San ...

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Average weekday ridership in October was down slightly to 171k, consistent with expected seasonal variation. Weekends saw a boost with Fleet Week and other special events. Saturday ridership, at 100,700 average exits, was 62% of pre-COVID expectations, and Sundays, at 70,900 average exits, was 63%.

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A: The level of BART service is determined by how much our budget can afford. We recoginze running more frequent service on nights and weekends would increase ridership. But we need more funding to pay the up front costs of running it.

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The BART server calculates the earthquake's seismic intensity within nanoseconds, and if the seismic intensity -- or MMI (Modified Mercalli Intensity Scale) -- is greater than IV, the server will automatically signal trains to reduce speeds. Trains then automatically begin slowing to 27 mph.

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You can bring your lunch or groceries onto a train, just please don't eat it, he said. BART has a no eating or drinking policy in the Paid Areas in an effort to keep the trains and stations as clean as possible.

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Downriver towns and major cities would see the most damage, in the event of the dam's physical collapse. Water flows would engulf many towns and growing cities around Mohave county, including Laughlin, Nevada; Needles, California; Lake Havasu, Arizona; and even as far south as Yuma, Arizona, and San Luis Rey, Colorado.

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It wouldn't be flooded, since the water would start draining southeast of the city and rush south down the Colorado canyon away from Las Vegas Valley. However, Las Vegas gets all of its water from Lake Mead, so the city would quickly dry up.

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If the Hoover Dam shuts down, it will have a ripple effect in the states of Nevada, Arizona, and California. There will be less water to go around, power will have to come from less clean sources, and all industries will be impacted some way or another.

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