BART Silicon Valley Phase II Extension

Alignment

Phase II extends BART about six miles beyond Berryessa/North San José, the terminus of the Phase I extension that opened in 2020, through downtown San José to the City of Santa Clara. It adds four stations: 28th Street/Little Portugal in East San José, Downtown San José at First Street, Diridon near SAP Center, and Santa Clara beside the Santa Clara Caltrain station. VTA forecasts 55,000 weekday riders. VTA is building the line and will hand it to BART to operate. The project also includes the Newhall Yard & Maintenance Facility in Santa Clara.

About five miles of the route is in a single large-bore tunnel, 53 feet in diameter. From an east portal near Las Plumas Avenue and Marburg Way, it runs parallel to US 101 to McKee Road, then under the freeway to 28th Street/Little Portugal. It curves onto Santa Clara Street near 27th Street and follows it for about two miles through Downtown San José to Diridon. West of Diridon it passes under Stockton Avenue, the Caltrain tracks at Emory Street and I-880 to the west portal at Newhall Yard, just south of Santa Clara station. The tunnel boring machine, a $76M machine assembled in Germany and owned by VTA, will be launched from the west portal.

The FTA issued the project’s Record of Decision in June 2018. VTA estimated the cost at $4.7B in 2014, $6.9B by 2020, $9.1B in 2022 and $12.2B in October 2023 before reaching the current $12.7B. VTA has secured roughly $12B, including a $5.1B federal New Starts pledge. It cannot apply for the federal funds until the budget balances.

Updates

2026-11 — VTA warns of a much higher cost and plans possible phasing

Project chief Tom Maguire said the new estimate, due at VTA’s oversight committee in late December, will be “significantly more” than $12.7B. Officials blamed fuel and material prices pushed up by the war in Iran and by tariffs. The start of tunneling, expected by the end of 2026, has tentatively slipped to early 2028, and it is unclear whether the 2037 target will hold. VTA is drafting an “adaptive plan” that could build the line in phases, though its leaders and San José Mayor Matt Mahan backed keeping all four stations. Maguire said VTA may not be able to apply for the federal funds for at least two more years and will study what it could build without them.

2026-07 — Construction contract converted to target price

The VTA board converted its construction contract with Kiewit Shea Traylor (KST) to a target-price, incentive-based model with open-book accounting. It authorized $400M for a first phase of early work and said further funding will need separate board approval. At the west portal, crews had finished the structure walls and about three-quarters of the excavation, and tunnel design was complete. Pre-construction work had started at the 28th Street/Little Portugal site, and soil testing was due to begin at Diridon.

2026-06 — Civil grand jury faults VTA oversight

A Santa Clara County Civil Grand Jury report criticized VTA’s management of the project. It noted that the FTA’s oversight consultant forecasts completion in 2039, not VTA’s 2037. VTA’s funding plan carried a $700M unfunded gap and assumed $375M from a proposed regional sales tax measure on the November 2026 ballot, for a total gap of $1.075B. The jury also found that Phase I had lost an average of $69M a year in its first five years of operation.

2025-10 — Board confirms the single-bore tunnel

After a peer review by tunneling experts from other transit agencies, VTA confirmed the single large bore as its preferred design. The alternative, two boring machines tunneling at once, would have needed cut-and-cover excavation downtown. VTA now owns the boring machine and plans to use Herrenknecht engineers to support its operation.

2025-06 — Tunnel contractor removed over cost

The VTA board voted to remove KST from tunnel construction after its cost proposals came in well over budget. KST was kept on to finish the early works already under way, including the tunnel launch structure. VTA planned to rebid the tunnel in several smaller packages.

2024-12 — Launch shaft contract approved

The board approved an amendment of up to $366.4M to KST’s tunnel and trackwork contract to build the shaft that will launch the boring machine. At the time VTA expected tunneling to start in 2027 and passenger service in 2037. Construction began at the Santa Clara station and west portal site on June 12, 2024.

2024-08 — Federal share capped at $5.1B

The FTA said it would contribute up to $5.1B, less than the $6.3B VTA had requested two years earlier, leaving a gap of about $700M. VTA began studying cost cuts that would keep all six miles and four stations. These included simpler stations, a reworked Newhall Yard, changes to the ventilation systems, surface parking instead of a parking garage, and a tunnel lining that uses less concrete and steel.