Caltrans will close ramps and lanes overnight on US-101 in Marin County for the Marin Sonoma Narrows B7 project. Closures are planned from Monday, December 15, to Thursday, December 18, 2025, between 10 p.m. and 6 a.m. each night. Additional lane closures are set for Friday, December 19. All work depends on weather conditions.
The De Long Avenue on-ramps in both directions will close from December 15 to 17. The Atherton Avenue on- and off-ramps will close on December 18. Detours will use Rowland Boulevard and Redwood Boulevard to guide drivers to alternate routes.
This work is part of the last phase of the 16-mile US-101 Marin-Sonoma Narrows program. The project will add continuous High Occupancy Vehicle (HOV) lanes from Sausalito in Marin County to Windsor in Sonoma County. Caltrans recently opened new HOV lanes, which now provide three lanes through the area…