‘Where the Journey Begins’: South Bay BART Extension Work Pushes Ahead

Plenty of questions remain about the long-running plans to extend BART through downtown San José and into Santa Clara: concerns about costs, schedule, disputes with contractors, and whether President Donald Trump might interfere with its federal funding are just some of the worries being weighed by local leaders.

Even as those questions persist, however, the first major construction since the $12.7 billion project was conceived decades ago is pushing ahead.

“We can see progress, and we have momentum, and we need to keep that momentum going,” said Tom Maguire, the chief megaprojects delivery officer for the Santa Clara Valley Transportation Authority, known locally as VTA.

The VTA is building the four-station, six-mile extension, which will eventually tie into existing BART service that currently terminates at the Berryessa/North San José Station, which opened in 2020, along with the Milpitas station.

New stations along the extension are planned for 28th Street/Little Portugal, Downtown San José at First Street, Diridon Station and the current Santa Clara Caltrain station.

Project officials said over roughly the past month, major excavation work has ramped up at the West Portal site on the border of San José and Santa Clara, near PayPal Park and San José Mineta International Airport.

Contractors are digging out a large ramp leading down to a 133-foot hole in the ground, which is being reinforced with huge rebar cages filled with concrete, some of which required a 217-foot crane and specialized equipment to drop into place.

“We’re rapidly opening up the ground. And for the first time, folks who have been waiting for this project for decades can start to see where the trains they’ve been paying for and hoping for are actually going to run,” Maguire said Monday morning during a media tour of the West Portal site.

The massive hole, and most of the construction happening around it, is in service of what’s called the launch structure. It’s where a $76 million tunnel boring machine recently assembled in Germany will eventually be dropped 82 feet into the earth to begin chewing through miles of muck.

It’ll bore out a 53-foot diameter tunnel shaft for five of the six miles of the extension, which will eventually contain train tracks, platforms and stairs or escalators for future passengers.

“Right here beneath our feet, we’re building the gateway that will connect BART to downtown San José and Berryessa and beyond,” Sarah Wilson, the construction director for the project, said during the tour. “This is where the journey begins, literally and symbolically.”

The vast expanse of the ramp is reinforced with large, cylindrical steel braces, which will help hold back the earth during construction and further excavation.

Small teams of workers on the ground were seen Monday morning coordinating with backhoe operators to check the integrity of the braces and fit them into place.

Maguire and other officials have emphasized the importance of getting the tunnel built as soon as possible as a means to help ensure the project doesn’t incur any further cost or schedule overruns.

The project, originally estimated by VTA in 2014 to cost about $4.7 billion and be completed in 2026, has ballooned in cost multiple times to its current figure, and is currently estimated to be completed sometime in the year 2037.

“It’s a significant project, it’s going to take a decade to build it, but the best way we can shrink that timeframe is getting this launch structure done and getting the tunnel boring machine moving as fast as possible,” Maguire said.

But even as the crews of anywhere between 30 to 80 workers toil on rotating shifts at the West Portal site 24 hours a day, VTA is seemingly already off the optimal mark.

Its tunnel boring machine just recently finished quality assurance testing in Germany, and is being disassembled to be packed away in storage before eventually being shipped to San José.

However, Maguire said Monday the launch structure won’t be complete until spring 2027, and a series of other jobs need to be completed on the site before the machine can be brought to the site and start digging, including setting up major power supplies to run it.

Wilson said VTA estimates tunneling won’t begin until either 2028 or 2029, and could take roughly three-and-a-half years to complete, barring any significant delays from unforeseen challenges.

Part of the delay stems from the agency’s decision to ditch its main tunneling and trackwork contractor over a cost dispute. That so-called “offramp” the agency elected to take could be responsible for up to an 18-month setback, Maguire said earlier this year.

It’s unclear at this point if VTA will find another contractor altogether or renegotiate with its previous partner to get the major tunneling work done, as some outside transit consultants have recommended they do.

Maguire said there’s been a lot of interest shown by the industry in the job.

“All the major tunneling contractors around the globe who are capable of doing this work are interested in doing this work,” he said. “Lots of people want to be part of this project. It’s a once-in-a-generation project.”