California Department of Transportation

11/03/2025 | Press release | Distributed by Public on 11/03/2025 17:58

Ramp, Lane Closures on Northbound, US-101 as Part of Marin Sonoma Narrows B7 Project in Marin County

Ramp, Lane Closures on Northbound, US-101 as Part of Marin Sonoma Narrows B7 Project in Marin County

Published: Nov 03, 2025

Schedule: Monday, Nov. 3 through Friday, Nov. 7 from 9:30 p.m. until 5 a.m.

Marin County - Caltrans has scheduled electrical work on Northbound US-101 for the Marin Sonoma Narrows B7 project from Monday, Nov. 3 through Friday, Nov. 7 from 9:30 p.m. until 5 a.m. the next mornings.

From Monday, Nov. 3 through Wednesday, Nov. 5, the San Antonio Road on- and off-ramps on Northbound US-101 are scheduled to be closed.

Lanes on US-101 are scheduled to be closed on Northbound US-101 during Monday through Friday timeline. At least one lane will be open for traffic.

All work is weather dependent.

Detour for on- and off-ramp closures for San Antonio 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

Daytime access will be available for motorists.

On Monday, Sept. 29, Caltrans opened the long-awaited, continuous HOV lanes (third lanes) on Northbound and Southbound US-101. This was another major milestone for the project. This work removed merges on Northbound US-101 (just north of Atherton Avenue) and Southbound US-101 (south of Kastania Road), which opened three continuous lanes through the project limits.

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.

For 24/7 traffic updates, follow 511.org: https://twitter.com/511SFBay For real-time traffic, click on Caltrans QuickMap: https://http://quickmap.dot.ca.gov/

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California Department of Transportation published this content on November 03, 2025, and is solely responsible for the information contained herein. Distributed via Public Technologies (PUBT), unedited and unaltered, on November 03, 2025 at 23:58 UTC. If you believe the information included in the content is inaccurate or outdated and requires editing or removal, please contact us at [email protected]