The Mare Island Causeway Bridge in Vallejo is closed to boats until crews replace a broken metal coupling that helps raise and lower the 1934 drawbridge, the city said Wednesday, Oct. 21. The single westbound lane into Mare Island remains open to cars and trucks.
Why it matters:
- The coupling is a specialized part that could require custom fabrication, so there is no date for the drawbridge to reopen to marine traffic.
- Another full closure of the bridge will be scheduled after the part is replaced.
- Overall repair completion is now set for March 2027.
What went wrong
On Saturday, Oct. 17, the city closed the 165-foot bridge to all traffic from 9 a.m. to 3:45 p.m. to fix a mechanical imbalance on the east side of the span that had caused a vertical misalignment. Vehicles were detoured to the Highway 37 Napa River Bridge.
That repair didn't work, and crews then found the broken coupling, Bay City News reported. Only after the coupling is replaced can crews go back to fixing the imbalance.
Walkers and cyclists
The bridge is closed to pedestrians and cyclists on weekdays through Friday, Oct. 23, while crews apply polyester concrete and methacrylate to the deck. The city says those materials contain chemicals classified as carcinogenic and can cause strong odors, headaches and nausea; the trails under the bridge are closed during the work too. It reopens to walkers and bikes each Friday around 5:15 p.m. and on weekends.
Alternatives: the San Francisco Bay Ferry between Mare Island and the Vallejo terminal, or the Highway 37 Napa River Bridge, about a 2.6-mile detour. The city also advises open-deck boats to avoid passing under the bridge 7 a.m. to 5 p.m. on weekdays.
A long-running project
Work started in August 2025. It slowed this summer because the threatened California black rail was nesting in nearby wetlands, and the city said in September the project was about 68% complete. Drivers heading toward Highway 37 should also note the separate Highway 37 Sears Point closure Oct. 23-26.