BART's San Jose extension finishes the 83-foot shaft where tunnel boring will start in 2028

The hole that will send a tunnel boring machine under downtown San Jose is finished, giving the long-delayed BART Silicon Valley extension one of its first visible structures, San José Spotlight reported Thursday.

Crews with the Santa Clara Valley Transportation Authority completed excavation in September of an 83-foot-deep launch shaft on a former rail yard near PayPal Park, on the San Jose-Santa Clara line, and finished pouring its concrete in late October. An 1,100-foot ramp connects the shaft to the surface and will one day carry trains to and from the future Santa Clara station.

The tunneling itself is still more than a year off. The 53-foot-wide boring machine has to be shipped from Germany, rebuilt on site and lowered into the shaft, with digging expected to start in early 2028, according to the report.

VTA projects the machine will advance 30 to 40 feet a day and take about 40 months to carve the roughly 5-mile tunnel, which will serve four new stations, three of them in San Jose and the fourth in Santa Clara.

"You can really feel where the trains will go and imagine that someday a subway is going to run here," Tom Maguire, VTA's chief megaprojects officer, told San José Spotlight. VTA officials said workers have logged 3.7 million hours at the site without a serious injury.

Cost and timeline

The project's price and schedule have both slipped. When it was planned in 2014, the extension was expected to cost $4.7 billion and open in 2026. The estimate now stands at $12.7 billion, with service projected to begin in 2037, according to the outlet, which cited pandemic-era material costs among the causes.

VTA is still working to close a gap of about $700 million left after a federal grant came in below expectations. Money from the regional transit sales tax that Bay Area voters approved this month is not slated for the BART project, San José Spotlight reported.

A civil grand jury has also criticized VTA's oversight of the project, saying it relied on uncertain funding and did not fully account for long-term operating costs.

Adam Cohen, a senior researcher at San Jose State University's Mineta Transportation Institute, urged residents to see the shaft as one step in a long process. "The project still faces notable engineering, construction, financial and other challenges," he told the outlet.

San Jose Councilmember Anthony Tordillos, who sits on VTA's board, called the work an exciting milestone that sets the stage for tunnel boring.

Sources

sanjosespotlight.com