BART turned 50 on Monday, and to celebrate, transit agency officials announced that seismic retrofits of the Transbay Tube are complete.
Officials say the BART system, which has carried millions of passengers across the San Francisco Bay Area for five decades, is now stronger and more resilient than ever.
“The best birthday present we could ask for,” a spokesperson said in a statement.
When the 3.6-mile-long tube between San Francisco and Oakland opened on September 16, 1974, it was the longest submerged tube in the world and was considered BART’s “most valuable asset.” But to withstand a major earthquake, BART said the tube needed to be upgraded. Those upgrades cost about $313 million and took about seven years to complete.
BART worked with seismic retrofit specialists using a combination of geotechnical and structural site studies, computer simulations and materials and model testing to develop the retrofit design, a spokesperson said.
At both ends of the tube are giant seismic joints that allow the two ends to move independently without damaging the structure. During the renovation, the original joints were modified to increase their movement capacity. Now, the two sides can separate further without seriously damaging the tube, according to a BART press release.
To educate residents about the Transbay Tube, its history and the engineering behind it, BART has released a new high-definition video offering a rare look inside from a train operator’s perspective.
BART also published a feature on the Transbay Tube, featuring interviews with the people who know it best, archival footage and ephemera from the BART archives, and a look at the science that keeps the tube from rusting.
There is also a video that allows viewers to get a close-up look at the tube and the engineering behind it.
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