On Friday, September 22, VTA Board members held the last of two workshops to study the complexities of delivering Phase II of the BART Silicon Valley Extension – a 6-mile, 4-station extension from the Berryessa BART station into Downtown San Jose and the City of Santa Clara.A

VTA has been in project development for Phase II for almost two years. After extensive environmental review and public feedback, VTA is closing in on finalizing the environmental document which must include the final project description. Throughout the environmental process, VTA carried different station location options for the Downtown and Diridon stations. There was also a comprehensive undertaking to study two different tunneling methods: a twin- or double-bore tunnel that exists currently on the BART system; and a single-bore tunnel that would house tracks running in both directions, either side-by-side or stacked on top of each other, in one tunnel.

A comprehensive analysis was conducted by independent third-parties and evaluation criteria were established to provide a qualitative and quantitative assessment of the options. Under consideration and study was: the feasibility to build and operate the configuration; what the impacts and benefits would be on economic development and the passenger experience; cost, and schedule.

After this in-depth analysis and public review process, the staff recommendation for the station locations is Downtown West and Diridon North. A Downtown West Station would provide long-term revitalization of the downtown core and provides excellent transit connectivity to existing transit. The Diridon North Station would maximize development potential in the area where there are great interest and growth.

At the Board workshop, after a presentation on the findings of the comparative analysis, staff presented the preferred tunnel option as being single-bore. The single-bore tunnel would contain tracks for both directions in a 45-foot diameter tunnel versus two 20-foot diameter tunnels. Passenger boarding platforms, cross passages used for emergency passenger egress, and other facilities would be constructed within the single-bore tunnel underground for all three underground stations. This tunnel configuration allows the construction work to be done out of the public right-of-way and without having to open up the street to do the excavation. This less disruptive, single-bore method would tunnel deeper underground which would also avoid much of the risk associated with encountering unknown utilities

At the Board workshop on Friday, the decision was made to have VTA, BART and consultant teams return to the VTA Board on October 5 to bring back further feedback on the tunnel recommendation for the Board to consider and approve. The Board must then certify the environmental document by January 2018 to submit the project to the Federal Transit Administration to be considered for federal funding.