Night Work for Ramp Closures on Northbound US-101 as Marin-Sonoma Narrows B-7 Project Continues in Marin County


Schedule: Monday, May 6 through the morning of Saturday, May 11

Marin Country — The Marin-Sonoma Narrows B-7 construction project continues in May with electrical work, which requires ramp closures on Northbound US-101 near Novato.

Map showing the location of the on-ramp and off-ramp overnight closures on northbound US-101 at San Antonio Road in Marin County.The San Antonio Road on and off- ramps on Northbound US-101 are scheduled to be closed from Monday, May 6 through Friday, May 10 from 10 p.m. until 6 a.m. the next mornings.

Daytime access near San Antonio Road will be available for drivers.

All work depends on the weather.

Detour for on- and off-ramp closures on Northbound US-101

  • San Antonio on-ramp closure: Drivers must enter on US-101 southbound at San Antonio Road, exit at the Atherton Avenue off-ramp and then re- enter US-101 northbound.
  • San Antonio off-ramp closure: Drivers must exit at Petaluma Boulevard South/ Kastania Road, enter US-101 southbound, and exit at San Antonio Road

This project reached another milestone on April 12, 2024, when traffic was shifted on US-101 in both directions from Novato near Olive Avenue to San Antonio Road.

Northbound US-101 traffic at San Antonio Road in Marin County.Southbound traffic was realigned away from the temporary median lanes, into the newly constructed Southbound US-101 road section. That section has been raised to match the median that was opened in June 2023. Northbound US-101 traffic was realigned into those same temporary median lanes now moving in the opposite direction, as the next phase of construction begins to reconstruct the old northbound road section.

Construction for the project includes widening US-101 to install HOV lanes for 3.5 miles along the northbound lanes from North Novato to the Marin, Sonoma line, and for 6.3 miles along the southbound lanes from De Long Avenue to the county line.

This is the last remaining High Occupancy Vehicle (HOV) lane construction project as part of the 16-mile US-101 Marin-Sonoma Narrows (MSN) program. This project will complete and allow continuous HOV lanes on US-101 from Sausalito in Marin County to Windsor in Sonoma County. HOV lanes are scheduled to be open to use in the summer of 2025.

Please drive with caution. Slow for the Cone Zone and Be Work Zone Alert. Caltrans thanks motorists for their patience while we work to maintain our state's highways, bridges, and tunnels.

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