Caltrans has announced ramp and lane closures on northbound and southbound US-101 in Marin County. These closures are part of the Marin Sonoma Narrows B7 project. Work is scheduled from Monday, December 8 through Friday, December 12, 2025. Closures will occur each night from 9:30 p.m. to 6 a.m. the next morning. The closures are for electrical work and are part of a project to widen the highway and add High Occupancy Vehicle (HOV) lanes.
Ramps affected include the San Antonio Road and De Long Avenue on-ramps in both directions, and the Atherton Avenue on- and off-ramps. The closure schedule varies by day. On December 8 and 9, the San Antonio Road and De Long Avenue ramps will be closed. Atherton Avenue ramps will close later in the week.
The construction area runs from just north of Rowland Boulevard to the Marin and Sonoma County line. Lane closures will also take place during the same overnight hours. All work depends on weather conditions. Drivers should expect delays and detours…