Tuesday, November 21, 2017

Panel recommends two tunnels for BART extension

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A comparison of the twin bore option, left, with the single bore option. A comparison of the twin bore option, left, with the single bore option. SCVTA

A peer review panel convened by Santa Clara Valley Transportation Authority (SCVTA) and Bay Area Rapid Transit (BART) has recommended a twin-bore option for a BART extension into Silicon Valley.


In early October, SCVTA announced the peer review panel would come together to weigh the single-bore and twin-bore tunnel options to help SCVTA's board reach a decision concerning the tunneling methodology for Phase 2 of SCVTA's BART Silicon Valley Extension. SCVTA says the panel consisted of transit agencies "with extensive experience in heavy rail operations, safety and maintenance."

According to SCVTA, the key question posed to the panel was "can the single bore tunnel be operated safely as an extension of the BART system and what risks and challenges are associated with the single bore configuration?"

While the panel concluded that the single-bore tunnel could be operated, it found key operational considerations related to fire/life/safety that would need to be addressed. Based on the available information, the panel recommended the twin-bore option would be preferred over the single bore to better meet BART's operating requirements.

"It is [SCVTA's] responsibility to deliver a project to the citizens of Santa Clara County that represents the best alternative in terms of safety, contractibility and operating efficiency," SCVTA said in a statement. "We certainly appreciate the preference of BART staff to operate in a manner to which they are accustomed and we are prepared to work with BART to explore these considerations."

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