Large Single Bore Tunnel for VTA's BART to Silicon Valley Phase II Extension

摘要

Santa Clara Valley Transportation Authority (VTA) is currently planning Phase 2 of the extension of the Bay Area Rapid Transit (BART) system into Silicon Valley, through downtown San Jose, California. A single bore tunnel configuration has been selected to allow two tracks and a center platform station to be located completely within the TBM tunnel lining. The resulting 5-mile long tunnel proposed for the project will have a nominal 54 ft outside diameter, passing through the dense downtown San Jose area and will include three underground stations. This paper summarizes the tunnel & station configurations, ventilation, Fire Life Safety, and constructability aspects of the project and discusses upcoming work.