VTA Completed Excavation for San Jose Transit Tunnel
The transit agency has launched a massive $76 million boring machine to advance the BART extension project.
Updated on Oct. 2, 2026 in Construction
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The Santa Clara Valley Transportation Authority has finished digging the 75-foot deep West Portal Launch Structure in San Jose. This milestone initiates the start of tunneling for the $12.2 billion BART Silicon Valley Phase II Extension Project.
Why it matters
The progression of this infrastructure work signals a shift toward active tunnel construction for a project that will eventually span five miles. For local firms, the movement of the tunnel boring machine marks a transition into a multi-year phase of heavy civil construction activity.
The BART extension has a $12.2 billion total budget, supported by a $490 million construction management contract. Crews are installing concrete lining segments weighing 40,000 pounds each at a rate of 54 per day.
The players
Santa Clara Valley Transportation Authority
The public agency responsible for planning, funding, and building transit infrastructure across Santa Clara County.
Kiewit Shea Traylor
A joint venture firm holding the primary contract for tunneling and track installation on the transit project.
Bechtel Corporation
A major global engineering and construction firm currently managing the $490 million construction management contract.
The details
The tunnel boring machine, which measures 54 feet in diameter, is now undergoing onsite assembly to begin a daily excavation pace of 30-40 feet. The Kiewit Shea Traylor joint venture manages the tunneling and track work, using a cutter-head system to remove debris while simultaneously placing the heavy concrete lining segments. This process will continue for three to four years until the five-mile subway tunnel is complete.
Timeline
2020: Phase I of the transit extension project opened.
2023: The VTA purchased the tunnel boring machine.
2024: Crews broke ground on the launch structure.
- 2026-10-02
Agency completed excavation for the West Portal.
2034: The Phase II extension project is slated for completion.
Market Landscape
The progress on the BART Silicon Valley Phase II Extension Project tracks with the capital-intensive nature of regional transit expansion. The shift into active tunneling follows the precedent of major multi-year civil works contracts currently reshaping the San Jose infrastructure market.
Operators in the San Jose area should anticipate multi-year traffic and logistics constraints as heavy machinery and large concrete shipments become standard. Businesses should evaluate how this long-term construction phase may influence localized supply chain access and client traffic patterns.
The takeaway
Large-scale infrastructure projects require years of site preparation before significant transit-capacity milestones are reached. Monitor the project's daily boring progress rates to forecast when heavy equipment activity will cycle through specific corridors in your operating territory.
What happens next
The tunnel boring machine is projected to maintain a steady advancement of 30-40 feet per day over the next three to four years, with final project completion scheduled for 2034.
Further reading
For more on local development shifts, see Construction.
Source note: This article includes information reported by Equipment World.
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