Save Article
South Bay transit officials in charge of building the $12.7 billion BART extension through downtown San José are doubling down on a single-tunnel design for the long-delayed megaproject, despite concerns from some engineering experts that conclusions made in a newly released report may lack “validity.”
Managers of the Santa Clara Valley Transportation Authority, which is building the 6-mile, four-station project for BART, say their plan to dig one of the largest underground tunnels on earth to house the train tracks and its platforms 80 feet below ground is still the best option.
They reaffirmed that determination on Monday, after the agency released what it called an independent cost, risk and impact analysis of a previously considered design that would use two smaller tunnels at a shallower depth — a more conventional approach to building subways in line with most of the existing BART system…