BART Silicon Valley Extension: Tunnel Boring Commences Amidst Contractual Shifts

Construction of the BART extension into Silicon Valley has officially begun, marked by initial groundwork and a strategic shift in tunneling contractors to optimize project costs.

BART Silicon Valley Extension: Tunnel Boring Commences Amidst Contractual Shifts

The BART Silicon Valley extension project has entered a new phase as heavy machinery initiates the excavation process at the Newhall Maintenance Yard. The Santa Clara Valley Transportation Authority (VTA) is overseeing the construction of this significant expansion, which promises to enhance regional connectivity.

Since June 9, contractors have been working around the clock, extracting bentonite—a clay-like material—from depths exceeding 80 feet. This process is crucial for erecting the launch structure that will support the tunnel boring machine (TBM). The VTA plans to deploy a single-bore tunneling method for the 5-mile segment beneath downtown San Jose.

Early preparations for the 6-mile extension, encompassing an underground tunnel and four new stations across San Jose and Santa Clara, commenced in February 2024. The project’s estimated cost is $12.75 billion.

Kiewit Shea Traylor initially handled preliminary work, including the launch station’s construction. However, the BART Silicon Valley Phase II Oversight Committee has endorsed recommendations to seek a different contractor for the tunneling phase. This decision follows a failure to reach a consensus on pricing between the VTA and Kiewit Shea Traylor. The VTA Board of Directors will review this recommendation at an upcoming meeting.

VTA’s project director, Tom Maguire, indicated that while specific savings are not yet quantified, discussions with ten potential contractors suggest significantly lower cost estimates than those proposed by Kiewit Shea Traylor.

The project received a $5.1 billion federal grant in April 2024, covering approximately 40% of the total cost. Despite this substantial funding, the VTA still faces a roughly $1 billion gap. Cost-saving measures, such as design modifications to the four stations and converting parking structures to surface lots, have already saved around $400 million.

Sarah Wilson, VTA’s Construction Director, confirmed that the ongoing construction of the launch structure will proceed regardless of the tunneling contractor. Completion of the launch structure is expected to take about two years. The current construction schedule runs from 6 a.m. to 4 a.m., and the VTA is seeking approval to extend these hours to a full 24-hour cycle.

Noise barriers and dust control measures are in place to mitigate disruptions to nearby residents and businesses. Wilson encouraged those with concerns to contact the VTA hotline. The agency anticipates selecting a new tunneling contractor before 2027. While this may delay tunneling progress, the target opening date for the extension remains 2037.

Maguire emphasized the focus on accelerating tunnel construction and streamlining other aspects of the project, such as station and platform construction, to minimize overall timelines. The VTA remains confident in achieving its objectives.

Keywords: BART Silicon Valley extension, VTA, tunnel boring, construction, San Jose, Santa Clara, infrastructure, transportation, Kiewit Shea Traylor