Santa Clara VTA confirms single bore as preferred tunnel configuration for BART Silicon Valley Phase II Project
The Santa Clara Valley Transportation Authority (VTA) has confirmed the large single bore as the preferred tunnel configuration for the Bay Area Rapid Transit (BART) Silicon Valley Phase II Project following a peer review conducted by tunneling and transit experts from major transit agencies across the country.
Santa Clara VTA says the single bore offers the best balance of constructability, feasibility and lower overall risk, as it avoids the high cost, complexity and downtown disruption associated with an alternative concurrent tunneling approach of using two boring machines, as the alternative would have required a cut-and-cover excavation.
With the single bore being confirmed, the project can now move towards 60% completion, keeping the project on track to meet its expected revenue service start date.
The panel that presented its findings to the board also recommended how Santa Clara VTA can ensure better cost estimation, accuracy and budget alignment while reducing schedule delays and managing tunnel risk. Since the agency now owns the tunnel boring machine (TBM), it’s fully responsible for managing the TBM’s performance. To help with this, Santa Clara VTA says it plans to enlist a leading tunneling team and utilize Herrenknecht’s engineers for operation support.
Santa Clara VTA notes it plans to continue engaging with the industry to ensure qualified, experienced construction teams submit a bid to build the project. The agency is also working to develop a contract strategy to encourage more bids.
The project will extend BART service six miles into downtown San Jose and Santa Clara, Calif., supporting state and regional goals around congestion relief, equity and economic development. The estimated $12.7 billion project is being funded through a combination of local, state and federal sources, including a planned nearly $5.1 billion contribution from the Federal Transit Administration’s New Starts program.