Caltrans will close one westbound lane on the Richmond-San Rafael Bridge overnight Friday, Sept. 25, for federally mandated bridge inspections.

Lane 1 on the westbound upper deck of I-580 will shut down from the Toll Plaza to the Marin County line between midnight and 5 a.m., according to a Caltrans District 4 advisory published Monday, Sept. 21. Lane 2 and the bike path will stay open.

Drivers should note a discrepancy in the posted end time. The official Caltrans advisory lists 5 a.m., while 511 SF Bay and a Caltrans District 4 Instagram post both list 4:30 a.m.

The Sept. 25 closure affects Lane 1, a different lane than several earlier September shutdowns. Closures on Sept. 8–11 shut down Lane 2 for the Open Road Tolling Project and deck maintenance work, as we reported Sept. 8. A Lane 2 closure on Sept. 12 was also tied to deck maintenance. Lane 1 was closed overnight Sept. 18 as well.

The Open Road Tolling Project is replacing existing toll booths with electronic tolling infrastructure. It is tentatively scheduled for completion in summer 2027, according to Caltrans District 4.

A separate Middle Mile Broadband Project is also driving overnight work on the bridge. Crews are installing nearly 50,000 linear feet of fiber-optic cable along I-580, with that project scheduled to run through Oct. 15, according to Caltrans.

Caltrans said motorists should expect minor delays, reduce speed, prepare to merge and allow extra travel time. Changeable message signs will alert drivers of the closure. All work is weather dependent and subject to change.

Drivers can check real-time traffic conditions at 511.org, through the Caltrans QuickMap tool at quickmap.dot.ca.gov, or by calling 1-800-427-ROAD. Caltrans also offers an email list for Richmond-San Rafael Bridge closure updates, available through the District 4 advisory page.