VTA OKs tunnel-boring machine for BART extension project

The Santa Clara Valley Transportation Authority has authorized the purchase of a transit-tunnel boring machine to complete the 5-mile underground section of the VTA BART Silicon Valley extension into downtown San Jose and Santa Clara, California.

VTA's contractor Kiewit Shea Traylor ordered the $76 million custom-built tunnel boring machine from Herrenknecht, a company specializing in customized tunneling equipment for projects around the world, VTA officials said in a news release.

The boring machine will dig the largest, single bore transit tunnel in the world, nearly 54 feet in diameter, capable of digging 30 to 40 feet a day.

The machine will be designed, manufactured, assembled and tested by the manufacturer at its German factory, and then will be disassembled for shipping. The components will then be shipped to Santa Clara County and reassembled at the project’s West Portal/Newhall Yard, where the tunnel work will begin in 2025. It's projected to take the machine about three to four years to complete the tunnel.