Did VTA environmentally clear the twin-bore tunnel? What would happen if VTA were to switch to the twin-bore tunnel now?

In early April 2018, the VTA Board of Directors approved VTA’s BART Silicon Valley Phase II Extension (BSVII) Project, certified the Final Subsequent Environmental Impact Report (SEIR) as CEQA lead agency, and selected the Single-Bore Option in the approved Recommended Project Description. In late April 2018, the BART Board of Directors, as a Responsible Agency under CEQA, accepted the SEIR and, pursuant to the Comprehensive Agreement, approved the BSVII Project as approved by the VTA Board, which included the selection of the Single-Bore Option. In June 2018, FTA, as the NEPA lead agency, issued the Record of Decision for the BSVII Project (approving the Final Supplemental Environmental Impact Statement) and selected the Single-Bore Option. Although the Draft 2016 and Final 2018 SEIS/SEIR included an evaluation of the Twin-Bore Option, it was not selected as the preferred option. Only the Single-Bore Option was selected as part of the approved project description. Also, although the VTA Board has approved the twin-bore design configuration in the past (in 2004 and 2007), only the single-bore design configuration has NEPA/CEQA clearance as of the 2018 approvals. Further information and documentation can be found in our Planning and Environmental page

In 2008, before the BART Extension Program was broken into two phases, a twin bore configuration with cut-and-cover stations was relatively advanced. However, those plans are now nearly 15 years old and would require major updates and redesign to meet the current codes and standards in addition to a new environmental clearance process. This would add years to the schedule and further delay revenue service. 

With only a few months to go before VTA anticipates awarding the first major construction contract for the project, such a change would add significant schedule and cost impacts and negate all the efforts and benefits of participating in the FTA Expedited Project Delivery funding program. Any potential cost savings, if determined, would also be exponentially negated with schedule delays and escalation.