Southgate Road on Treasure Island


The Yerba Buena Island/I-80 Southgate Road and Interchange Project reconstructs the I-80 eastbound off-ramp to Yerba Buena Island. The project features an innovative design that enhances safety and circulation.

This project is part of a larger effort to replace and retrofit key roads and on- and off-ramps that connect the I-80 (the highway on the Bay Bridge) and Yerba Buena Island.

The Transportation Authority is working jointly with the Treasure Island Development Authority on this effort. These upgrades will support the Treasure Island Transportation Program.

Notice about Bike/Pedestrian Access to Treasure Island

See details about Treasure Island access.


Project Map

An aerial view of the new road configuration


  • June 2020

    Construction begins

  • May 2023

    Construction ends

Cost & Funding 

Funding for the $61 million project comes from the Federal Highway Bridge Program and State Prop. 1B facilitated by Caltrans, with local matching funds provided by the Bay Area Toll Authority, and the Treasure Island Development Authority.



Key features

In collaboration with the Treasure Island Development Authority, the project features an innovative design that will improve traveler safety for motorists, cyclists, and pedestrians and enhance traffic circulation by:

  • Building the I-80 Bay Bridge eastbound off-ramp to seismic standards and connections to the Transportation Authority’s award-winning YBI East Side Ramps Project that provided westbound Bay Bridge access to the Islands in 2016;
  • Redesigning the YBI/I-80 Southgate Road circulation to separate vehicle traffic from bicycle and pedestrian paths and accommodating heavy duty vehicles and trucks; and
  • Creating dedicated bicycle and pedestrian facilities that connect East Bay travelers arriving to Yerba Buena Island Vista Point (from the Bay Bridge East Span Bike/Pedestrian path) to Treasure Island via Macalla Road.

The project is the second of three projects led by the Transportation Authority designed to replace and retrofit key roads and ramps linking the islands to I-80. The first project was the I-80 East Side Ramps project, completed in 2016. After the Yerba Buena Island/I-80 Southgate Road and Interchange Project, the Transportation Authority will lead the West Side Bridges Retrofit

Disadvantaged Business Enterprise goal: The construction firm for the project, Ghilotti Construction Company Inc., has committed to direct almost 17 percent of the budget to disadvantaged business enterprises. Work for DBE firms may include demolition, excavation, erosion control, noise monitoring, landscaping, traffic control, and trucking. 

Related programs


The Treasure Island Transportation Program will address the island's growing transportation needs with a goal to have at least 50 percent of trips made by transit instead of private vehicles.

The new westbound I-80 on- and off-ramps that connect Yerba Buena Island and Treasure Island to the eastern span of the Bay Bridge are open.

The West Side Bridges Retrofit will seismically retrofit eight existing bridge structures along Treasure Island Road to meet current seismic safety standards.

Vista Point is a scenic rest stop on Yerba Buena Island near the Bay Bridge east span bicycle/pedestrian path.