VTA Completed West Portal Launch Structure Excavation
Construction crews have finished the deep excavation required to launch a massive tunnel boring machine in San Jose.
Updated on Oct. 2, 2026 in Construction
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The Santa Clara Valley Transportation Authority has completed the excavation of the West Portal Launch Structure for the BART Silicon Valley Phase II Extension Project. Located 75 feet underground, the site serves as the starting point for a new five-mile subway tunnel.
Why it matters
This milestone initiates the active tunneling phase of the $12.2 billion project, which aims to expand regional transit capacity to a projected 55,000 daily riders. Finishing the launch structure is a critical requirement for assembling the heavy equipment needed to bore beneath the city.
The project features a $76 million, 54-foot diameter tunnel boring machine that will advance at a rate of 30-40 feet per day. The effort involves installing 54 concrete lining segments daily, each weighing 40,000 pounds.
The players
Santa Clara Valley Transportation Authority
This is the primary public agency responsible for planning, designing, and operating transit services in Santa Clara County.
Kiewit Shea Traylor
This joint venture serves as the lead contractor responsible for the execution of tunneling and track work.
Bechtel Corporation
This global engineering and construction firm provides professional management services for large-scale infrastructure projects.
The details
The project utilizes a massive cutter-head that rotates to break ground while debris is removed through a dedicated conveyor system. Kiewit Shea Traylor manages the tunneling work, while the Bechtel Corporation oversees the construction management under a $490 million contract.
Timeline
2020: Phase I of the extension project opened.
2023: VTA purchased the tunnel boring machine.
2024: Crews broke ground on the launch structure.
October 2, 2026: Excavation of the West Portal Launch Structure was completed.
2034: Scheduled completion date for the Phase II extension project.
Market Landscape
This project represents a massive regional infrastructure investment that aligns with long-term transit expansion goals across the Bay Area. It marks a significant shift in local transit development as the agency transitions from surface-level planning to heavy underground construction.
As construction intensifies, residents should prepare for long-term site activity and potential traffic disruptions around the tunnel portal locations. The project is a long-term investment intended to provide a future alternative for 55,000 daily commuters in San Jose and Santa Clara.
The takeaway
The project represents a multi-year effort to modernize transit that will fundamentally alter regional connectivity upon its 2034 completion. Residents and commuters can expect persistent construction zones for the next decade as tunneling work progresses beneath the city.
Further reading
For more background on major regional infrastructure developments, see our coverage of Construction.
Source note: This article includes information reported by Equipment World.
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