Date and Time: Tuesday, July 7, 2026,
District/Agency: Solano Transportation Authority, City of Vallejo, Caltrans District 4 – Bay Area, Solano County
Contact: Sean Person, Sabrina Martinez
Phone: (707) 399-3217, (510) 934-5257
Email: sperson@sta.ca.gov, sabrina.martinez@dot.ca.gov
STA, Caltrans, and Local Representatives Celebrate the Opening of the Bay Area’s First Diverging Diamond Interchange in Vallejo
VALLEJO, CA – Today, with over 100 attendees standing near the famed Six Flags Discovery Kingdom Medusa Coaster, the Solano Transportation Authority (STA), in partnership with the California Department of Transportation (Caltrans), the City of Vallejo, the Metropolitan Transportation Commission (MTC), Solano County, Six Flags Discovery Kingdom, and elected officials hosted a ribbon cutting event to mark an important milestone for project partners, the Vallejo community and other nearby North Bay communities. The event celebrated the recent installation of an innovative Diverging Diamond Interchange (DDI) that enhances safety, reduces congestion, and supports easier access for motorists, pedestrians, cyclists, transit users, and the surrounding communities.
The DDI is the first of its kind in the Bay Area and only the second in the State of California to open to traffic.
“The Diverging Diamond Interchange reimagines the State Route 37 corridor as a gateway to the broader Resilient 37 Project, which will address flooding, sea level rise, bay restoration, traffic congestion, and multimodal access,” said Caltrans Director Dina El-Tawansy.
“The new Diverging Diamond will improve how people move through Solano County on foot, by bike, in a car, or via transit! This project also supports the future development like Solano 360 and connections to a planned mobility hub,” said Solano County (District 1) Supervisor, Cassandra James.
“By leveraging established relationships with regional partners, the Solano Transportation Authority is delivering a new Diverging Diamond Interchange designed to move cars, bicycles and pedestrians more safely and efficiently through Vallejo,” said STA Board Chair and Mayor of Suisun City, Alma Hernandez.
The newly redesigned interchange at the intersection of State Route 37 and Fairgrounds Drive improves traffic flow and safety while reducing congestion. The innovative Diverging Diamond Interchange design reduces conflict points by eliminating left turns against oncoming traffic. The result is both safer and easier for motorists, pedestrians, and cyclists to access and navigate.
Construction at State Route 37 (SR 37) and Fairgrounds Drive started construction in April 2025. The new DDI represents a major investment in safer, smarter, and more connected travel through Vallejo and Solano County, representing one part of the greater Resilient SR 37 Project.
The Solano Transportation Authority, in partnership with the City of Vallejo, Caltrans, and Solano County, led construction on the State Route 37/Fairgrounds Drive Interchange Improvements Project. This project supports Solano 360, a larger regional effort to revitalize the area and encourage economic growth and development. It is funded by Regional Transportation Impact Fee (RTIF) Program and the Metropolitan Transportation Commission (MTC), which has committed $18 million in funding through Regional Measure 3.
For more information, visit the State Route 37/Fairgrounds Drive Project webpage:
https://sta.ca.gov/project/redwood-parkway-fairgrounds-dr-improvement-project/
