The West Side Bridges Retrofit will seismically retrofit eight existing bridge structures along Treasure Island Road to meet current state seismic safety standards. These bridge structures are a critical connection between Yerba Buena Island, Treasure Island, and the Bay Bridge.
This construction project is part of a larger multi-modal infrastructure improvement program on the Islands. The first two projects were the I-80 East Side Ramps Project (2016) and the Yerba Buena Island/I-80 Southgate Road and Interchange Project, opened in 2023.
The Transportation Authority is working in partnership with FHWA, Caltrans, BATA and the Treasure Island Development Authority on these efforts. These upgrades support the Treasure Island Transportation Program.
Environmental clearance; final design and right of way certification
The Transportation Authority is leading the design and construction of this project in collaboration with the Treasure Island Development Authority.
Cost & Funding
The cost of the West Side Bridges Retrofit is $126 million. Funding for the project comes from a combination of federal, state, and local sources, including the federal Highway Bridge Program, federal Rebuilding American Infrastructure with Sustainability and Equity Grant, California Prop 1B Local Bridge Seismic Program, Bay Area Toll Authority, SB 1 Local Partnership Program Formula Funds, Treasure Island Development Authority, and Transportation Authority Prop K Transportation Sales Tax.
|Federal Highway Bridge Program (HBP)
|State Prop 1B Local Bridge Seismic Program (match to HBP)
|Federal RAISE Grant
|Bay Area Toll Authority (BATA) Toll Bridge Rehab
|BATA SB 1 Local Partnership Program Formula Funds
|SFCTA SB 1 Local Partnership Program Formula Funds
|SFCTA Prop K
In support of the Islands’ development plans, the West Side Bridges project seismically upgrades the west-bound I-80 Treasure Island Interchange and Road, and improves safety and circulation for motorists as well as for travelers on bicycle and transit.
The project features:
- Seismic upgrades to retrofit eight existing bridge structures along Treasure Island Road on the west side of Yerba Buena Island and I-80 Bay Bridge ramp improvements to meet current operational safety standards;
- Expanded bicycle access by creating a 6-foot wide bicycle lane with a striped safety buffer. The bikeway is the first step in the Bay Skyway Phase 1 project that will link both Treasure Island and Yerba Buena Island with the Transbay Bay Trail slated for the Bay Bridge;
- Improved bus access to the Islands with a dedicated west-bound bus / HOV (high-occupancy vehicle) on-ramp to the Bay Bridge; and
- Decorative retaining wall designed by Bay Area artist Muzae Sesay
At completion, the project will enable a one-way south-bound traffic circulation pattern for vehicles, connecting to the forthcoming Hillcrest Road Improvement project, which is presently under design. The West Side Bridges Retrofit project is being delivered via Construction Management/General Contractor project delivery method, and will employ over a dozen specialized construction trades.
The West Side Bridges Retrofit project is the third in a trio of ramp seismic safety projects led by the Transportation Authority designed to replace and retrofit key roads and ramps linking the Islands to the I-80 San Francisco-Oakland Bay Bridge. The first project was the I-80 East Side Ramps project, completed in 2016. The second was the Yerba Buena Island/I-80 Southgate Road and Interchange Project, completed in 2023.
Brief History of Treasure Island and West Side Bridges
Treasure Island was constructed during 1936-1939 and consists entirely of filled land. Both the Bay Bridge and the West Side Bridges were built starting in 1937. The West Side Bridges were built in part to support transportation by visitors to the Golden Gate International Exposition in 1939-1940 during Treasure Island’s first phase of development. Both islands have served as a military base for World War II and as a continuing U.S. Coast Guard facility. The Islands are transforming again as part of an effort to build up to 8,000 homes—many offered at below-market rates—housing more than 20,000 new residents.