San Francisco’s VTA has reached a significant milestones for extending the BART system that will include a 5 mile (8km) tunnel section to downtown San Jose and into Santa Clara with a $730M shot in the arm from California’s Senate Bill 1, the newly passed gas tax. Announced April 26th, in Sacramento, the California State Transportation Agency funding now helps pave the way to a $1.5bn request for federal funding to be made this summer for the $4.8bn project.
“The magnitude of today’s announcement cannot be understated, nor can the regional significance of this project,” said VTA General Manager and CEO, Nuria Fernandez, during the press conference held at the State Capitol.
Fernandez thanked State Senator Jim Beall, chair of the State Transportation and Housing Committee, for his leadership in helping to transform mobility in the San Francisco Bay Area.
In addition to the state funding, BART’s Board of Directors moved the Silicon Valley Extension project forward by approving a single-bore tunneling methodology for the 5-mile (8km) subway through downtown San Jose, and the two station options including Downtown San Jose West (between Market and Fourth Streets in downtown San Jose) and Diridon Station North (adjacent to the south side of In a West Santa Clara Street, between Autumn Street and the San Jose Diridon Caltrain Station.) The single bore is envisaged as being a 45ft (13.7m) diameter TBM driven tunnel.
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In a recent VTA statement, the single-bore design was described as meeting industry and BART facility standards for operations and safety, and that it would reduce impacts to street level activities and underground utilities that would occur with twin-bore construction. More specifically, the single-bore tunneling methodology, compared to the twin-bore option, will:
Result in limited excavation within the public street right-of-way, resulting in less construction impacts to businesses and the community during construction;
Reduce impacts to auto traffic, bicyclists, and pedestrians because it would not require the closure of Santa Clara Street and adjacent roadways during construction;
Eliminate impacts to VTA’s light rail service because the tracks crossing Santa Clara Street at 1st and 2nd streets would not have to be temporarily closed due to street-level excavation while constructing the downtown subway station; and
Provide greater operational flexibility, allowing for the ability to provide multiple crossover tracks and areas to store train cars within the tunnel for emergencies, special events, or regular maintenance activities.
A spokesperson for VTA told Tunnelling Journal, “The recent successful partnership between VTA and BART in analyzing and evaluating tunneling methodologies for the downtown San Jose Segment of the extension demonstrates that the two agencies can work together to improve mobility for the Bay Area.
“Both agencies are committed to ensuring that the single bore alignment will be a safe and reliable extension of the existing BART system.
“Specifically, VTA has assured BART that a single bore tunnel can be designed in a fashion that addresses safety concerns related to ventilation, braiding design, evacuation procedures and other life/safety issues.
“VTA has put in writing its commitment to guarantee BART final sign off on design.”
This vote was the last step before a federal funding request can happen.
Construction of the project is anticipated to begin in 2019 for completion in 2026