In just a few months, VTA’s Tunnel and Trackwork Contractor will begin early construction activities to prepare for the arrival of what’s known as “a Tunnel Boring Machine” (TBM), which is a massive machine used to create (“bore”) an underground tunnel. This preparatory work will occur at a project location called the West Portal, which is located within the Newhall Yard, the future location of the Santa Clara BART Station and Rail and Maintenance Yard. The West Portal is the launching point for the TBM, and the area around it will be utilized to support tunneling operations throughout construction. Preparation activities will involve:
- Creating access into the yard, designating parking, and ensuring access to office buildings
- Constructing and operating a tunnel lining factory to build the segments of concrete that will line the tunnel
- Assembling the tunnel boring machine
- Digging the tunnel portal
Once prepared, the West Portal area will be the central hub for storing and hauling soil from boring the 5-mile tunnel, and manufacturing and storing tunnel lining segments. Once tunneling is completed, the future Santa Clara Station and Newhall Yard Maintenance Facility will be constructed.
Early construction activities will occur for approximately two years, followed by tunneling and heavier construction. Details of several different types of early construction activities include:
- A tunnel lining factory where concrete “tunnel lining segments” will be manufactured to use during tunnel construction. About 360 tunnel lining segments will be fabricated prior to the arrival and launch of the TBM. This prep work is essential because the TBM will require using more lining segments daily than can be made on-site
- A Grout Plant will produce the grout used to seal together the tunnel lining segments when tunnel construction begins
- An “excavated materials bin” needs to be prepared so that, once tunneling begins, excavated materials can be stored properly until they’re hauled offsite to be repurposed or disposed of
- Employees will be parking on-site within the construction area. This will help ensure there is no “spill-over” parking into the surrounding neighborhoods
Fun fact: each concrete tunnel lining segment weighs about 40,000 lbs.!
During all phases of construction, VTA’s contractors will implement construction best-practices in accordance with environmental requirements to minimize noise and dust. Some of these methods include:
- Installing a noise curtain
- Covering trucks carrying loose materials
- Washing the trucks before they leave the construction site
- Removing visible dirt on adjacent public roads
- Suspending dust-intensive activities in high winds
- Installing screening around the work site
As part of the planning for early construction activities, VTA’s Tunnel & Trackwork Contract developed a Construction Transportation Management Plan (CTMP), which outlines potential transportation impacts due to construction and mitigations. The West Portal Early Works CTMP was developed in close coordination with and approved by both Cities of San José and Santa Clara in Spring 2023, as well as with key stakeholders in the area, including PayPal Park and Costco. No detours or lane closures are planned during early construction activities around the West Portal site. All pedestrian, bicycle, and vehicular facilities will be maintained in and around the site during construction. Construction signage and construction vehicles accessing the site will be visible along designated haul routes to or from I-880 along Coleman Avenue.
Project staff will continue to notify residents and businesses near the Project’s various worksites of construction activities through physical mailers, local flyering, email, social media posts, and website updates.
Community Engagement for Early Construction Activities at the West Portal
During the development of the CTMP, VTA held two public meetings to share information on the upcoming construction activities. An in-person public meeting was held at Santa Clara University on March 15th, and a virtual public meeting was held the following day. The virtual public meeting was recorded and is available online. The presentation materials for this public meeting are also posted on the project website.
*Please note that the construction schedule in the March 2023 Public Meetings was based on the latest schedule at that time.
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Five of the six miles to the VTA’s BART Silicon Valley Phase II Extension (BSVII) will be underground in a tunnel measuring approximately 50 feet in diameter. Constructing this tunnel via a single-bore approach allows for much of the Project’s construction to occur below ground, which reduces disruption to city streets neighborhoods and businesses compared to other tunneling methods. This approach also reduces the footprint needed for station construction.
Fun fact: VTA will be the first in the nation to use a single-bore tunnel design for transit. Other transit systems have been constructed this way in Europe and Asia, with recent projects in Spain, France, Dubai, and the Netherlands.
Over the years, VTA has continued to refine the design of the tunnel, coordinating closely with BART and industry experts. Most recently, in 2022, the Tunnel and Trackwork Contractor proposed a new tunnel configuration that would reduce the cost of construction while improving passenger experience. The resulting design is a slightly larger tunnel that accommodates side-by-side tracks throughout the alignment, with center platforms at the stations. This new design will provide consistent and intuitive circulation for passengers at all three new underground stations.
Learn more about tunneling and future construction activities on VTA's BSVII construction webpage!
Community Engagement Efforts
In the first half of 2023, Project staff attended 11 in-person community events resulting in engagement with over 1,000 members of the public. Most recently, project staff attended Viva Calle, Día de Portugal, MACLA’s Family Art Day, and the Spring Open House/Train Show at Santa Clara Depot. At these events, community members that stop by the Project’s booth can learn more about the Project and get one-on-one time with project staff.
To stay informed about future events please check the Project calendar and/or follow the Project on social media.
VTA’s BART Silicon Valley Phase II Extension project will continue to share newsletters with updates as construction progresses and continues to reach important milestones. Stay tuned for more exciting newsletters.
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