BART Warm Springs Extension

The 5.4-mile extension of BART commuter rail to a new station in Fremont, California makes it more convenient for commuters traveling to Oakland and San Francisco. The extension included a 1-mile tunnel under Lake Elizabeth in Fremont Central Park.


  • Fremont, California, USA


  • Bay Area Rapid Transit

Project Status

  • Opened in 2017

Extending BART

Prior to the Warm Springs extension, there was no public transportation link to BART south of Fremont and commuters had to travel to Fremont Station, where it was difficult to find parking. Warm Springs alleviates the parking problem with 2,082 parking spaces, and reduces traffic on the nearby I-680/I-880 interstate highways. An estimated 6,000-7,000 riders every weekday access the extension from Warm Springs/South Fremont station.

Although the extension and station were budgeted at $890 million, when the tunnel construction elements were bid the project stayed well below budget, while maintaining high quality, resulting in a savings of about $100 million below initial budget projections.

The station includes 42 solar-powered electric vehicle charging stations. Bike lockers and bike racks were also installed to ensure that the station is fully accessible by pedestrians and cyclists. It also provides a bus transit center to provide easy connections between the trains and Alameda-Contra Costa Transit (AC Transit) buses.

34 34
Daily Ridership
6,000 - 7,000 6,000 - 7,000
5.4 miles 5.4 miles

2,000 photovoltaic panels

The $54 million intermodal transit hub covers 34 acres and includes more than 2,000 photovoltaic panels on the roof and in the parking lots that can generate 512 kilowatt hours of energy – enough to meet the station’s daytime power needs. an eight-acre wetland site for environmental mitigation offsets the impact of the project.

The station’s modern design includes elevators and escalators that improve access to the elevated platform. It features local artistic elements, including “Sky Cycles,” a colorful art glass display on the station’s curtain walls created by artist Catherine Widgery. 

The extension design allows for the potential installation of a future platform station at Irvington, midway between Fremont Station and Warm Springs Station. Future plans also include extension of the rails farther south into San Jose and Santa Clara County.

BART Warm Springs station extension visualisation

WSP's Role

WSP had a comprehensive understanding of the design, as well as the technical expertise, so the firm was requested on numerous occasions to undertake site inspections to identify potential problems and make corrections before issues arose. “Since we knew the design very well, we were able to help BART successfully complete its testing and safety certification and make sure the client’s interests were always at the forefront,” says Tony Murphy from WSP.

The rail extension and new station in Fremont makes it more convenient for commuters to ride BART trains north into Oakland and San Francisco.

The list of primary WSP's services in design and construction-phase services on the Warm Springs Extension include civil, structural, rail systems and tunnel/geotechnical engineering, design support, right-of-way acquisition support and procurement support. We were responsible also for the preliminary engineering design of two rail lines, three control rooms, five track power facilities, and two box tunnels, including 100 percent design of the cut-and-cover tunnel under Lake Elizabeth in Fremont Central Park.

This was a complex project, so it was important that the design-build design accounted for what the BART stakeholders needed, and that the contractors understood their role. Proactive discussions with the contractor and BART, and an approach that involved working in the BART offices, helped us with problem identification and resolution. Personnel consistency helped to keep the owner informed and the project on track.
Tony Murphy WSP Project Manager

Challengers for an Intermodal Station

The rail extension provides BART commuters in San Jose with an important public transportation link to Oakland, San Francisco, and other points along the BART route. A section of the tunnel near Fremont Central Park passing by Hayward Fault, as well as an adjoining aquifer, posed a significant technical challenge.

To protect the tunnel from potential earthquake activity, WSP developed an innovative design that included seismic joints and a flexible, self-repairing waterproofing gel that allows the subway box to withstand a major earthquake while maintaining a relatively water-free environment inside the tunnel.

WSP developed an innovative tunnel design that included seismic joints and a flexible, self-repairing waterproofing gel that allows the subway box to withstand a major earthquake while maintaining a relatively water-free environment inside the tunnel.