VTA Achieves 75% Excavation on BART Silicon Valley Phase II Subway as KST Contract Shifts to Cost-Incentive Model at Diridon Station

BART Silicon Valley Phase II Reaches 75% Excavation Milestone

SAN JOSE, California — Transforming Bay Area transit integration, the Santa Clara Valley Transportation Authority (VTA) confirmed major civil engineering achievements in late September 2026 across the BART Silicon Valley Phase II Extension Project. Heavy construction crews working across key subterranean shaft sites in downtown San Jose have achieved 75 percent completion of primary earth excavation alongside the installation of heavy concrete structural diaphragm retaining walls and pressurized groundwater stabilization systems.

The six-mile extension represents the largest single transportation infrastructure undertaking in Santa Clara County history, extending BART heavy rail from the Berryessa/North San José terminus through an underground tunnel beneath Santa Clara Street to Santa Clara, featuring modern subterranean stations at 28th Street/Little Portugal, Downtown San José, and Diridon Station.

Contracting Transition Enhances Cost Transparency at Diridon Hub

To safeguard public investments and streamline multi-agency operations, the VTA Board of Directors finalized the formal transition of its primary tunnel and trackwork contract with joint venture Kiewit Shea Traylor (KST) to a Target Price and Incentive-Based contracting model. The refined framework enhances budget transparency, shares cost-containment incentives, and aligns engineering deliverables with municipal stakeholders across San Jose and the City of Santa Clara.

At the Diridon Station transit hub, specialized construction crews initiated temporary surface realignment and structural foundation piling. The station will serve as Northern California's preeminent multi-modal passenger junction, seamlessly uniting BART with Caltrain electrified express trains, the Altamont Corridor Express (ACE), Amtrak Capitol Corridor, VTA light rail, and regional bus rapid transit.

Community Engagement Forums Detail 60% Design Packages

During well-attended community briefings hosted at the Mexican Heritage Plaza on September 16 and subsequent technical sessions, VTA project engineers presented 60 percent design packages detailing station ventilation, accessible elevators, and architectural pedestrian plazas. City leaders commended the rigorous engineering standards, affirming that closing the BART transit ring around the Bay establishes an enduring spine for clean regional mobility and Silicon Valley economic growth.