Thursday, October 05, 2017

BART to Silicon Valley: One tunnel or two?

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BART to Silicon Valley: One tunnel or two? SCVTA

Santa Clara Valley Transportation Authority (SCVTA) and Bay Area Rapid Transit (BART) will conduct a peer review of two tunnel methods as part of a planned BART extension to Silicon Valley.

The peer review will commence this month by public transit agencies currently operating rail subway systems and weigh a single-bore and twin-bore tunnel options for the five-mile tunnel. SCVTA and BART expect the peer review to take several weeks.

The single-bore tunnel under consideration would be a deep, 45-foot diameter tunnel incorporating both the trackway and the stations within it. The second option is a twin-bore tunnel that includes two, 20-foot diameter tunnels with stations and a wide center platform.

BART Silicon Valley Phase II is an extension of the regional BART system that will further expand the system from the nearly completed Berryessa Station in northeast San Jose and add three stations in San Jose and an end-of-line station in Santa Clara. SCVTA designing, funding and building the extension and BART will operate the system once built.

SCVTA and BART entered into a comprehensive agreement in 2001, relating to the design, construction, operation, and maintenance of the BART extension in Santa Clara County. The project is currently in the state and federal environmental analysis process and is on track to receive the final federal environmental clearance in March 2018 to deliver the project by 2026.

The project's draft environmental impact document, released for public comment in December 2016, includes options for the Diridon and Downtown San Jose stations and tunnel methodology. The final state and federal document is expected to be released in early December 2017. To ensure consistency with the California Environmental Quality Act (CEQA), a Board decision on the project options analyzed will be made in January after the Board has received and reviewed all of the information contained in the final environmental document and reviewed the conclusions of the peer review.

The $4.7-billion project will be funded through a combination of local, state and federal funding. Once completed, Phase II of SCVTA's BART Silicon Valley Extension will extend six miles from the future Berryessa/North San Jose Station, through San Jose and into Santa Clara.