Decision Deadline Coming Fast for San Jose BART Extension

The four-station San Jose BART extension will be one of the largest extensions the system has ever received, but what those stations will look like is still up for debate. "Not only will it link the economic powerhouse of Silicon Valley to the East Bay and San Francisco, it will also connect BART to Caltrain and high-speed rail, transforming San Jose into a regional transit hub unlike any the Bay Area has ever seen," Erin Baldassari and Emily Deruy write for The Mercury News.

The decision comes down to the difference between a twin-bore or single-bore solution for tunneling. The more common twin bore would cut two tubes for trains to run on parallel tracks, with a platform in the middle. The single-bore alignment would cut one large tunnel and put the two tracks above one another. "To get funding and start construction in the next two years, the VTA’s governing board needs to make its decision by April 5, and BART must approve that recommendation by April 26," Baldassari and Deruy write.

The two approaches have different features, the single-bore solution, which the Valley Transportation Authority (VTA) favors, would be a deeper cut and disrupt the street and utilities less during the construction period. A double-bore tunnel would have a larger platform and, because it wouldn't be different from other tunnels in the system, it would be less likely to cause confusion in the event of an emergency evacuation, BART officials contend.