BART turned 50 years old on Monday and, to celebrate, transit agency officials announced that the earthquake retrofit of the Transbay Tube is complete.
Officials say the BART system, which has ferried millions of passengers across the San Francisco Bay for five decades, is now stronger and more resilient than ever.
“The best birthday gift we could ask for,’’ a spokesperson said in a statement.
When the 3.6 mile-long tube between San Francisco and Oakland opened on Sept. 16, 1974, it was the longest immersed tube in the world and it’s been deemed BART’s “most valuable asset.” But to withstand a major earthquake, BART said the tube needed upgrades. Those improvements cost about $313 million and took about seven years to complete.
BART worked with earthquake retrofit specialists using a combination of geotechnical and structural site investigations, computer simulations and testing of materials and models to develop the retrofit design, a spokesperson said.
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At both ends of the tube, there are giant seismic joints that allow the two ends to move independently without damaging the structure. During the retrofit, the original joints were modified to increase their movement capacity. Now, the two sides can separate further without major damage to the tube, according to a news release from BART.
To educate residents about the Transbay Tube, it’s history and the engineering behind it, BART has released a new high-definition video offering a rare glimpse inside from the vantage point of a train operator.
BART has also posted a story about the Transbay Tube, featuring interviews with the people who know it best, archival images and ephemera from the BART archive and a look at the science that prevents the tube from rusting.
There is also a video that gives viewers a close look at the tube and the engineering behind it.