New High Occupancy Vehicle (HOV) Hours to go into Effect on Monday, Sept. 8 in Marin, Sonoma Counties on US-101

Schedule: New hours are 5 to 10 a.m. in the mornings and 3 to 7 p.m. in the evenings

Marin County And Sonoma County — This weekend, crews are scheduled to finish switching out high-occupancy vehicle (HOV) signs along Northbound and Southbound US-101 in a 52-mile stretch as part of the final steps of the Marin Sonoma Narrows B-7 project. Signs along the corridor are being modified or replaced with signs displaying new uniform carpool hours.

On Monday, Sept. 8, the new HOV lane hours will take effect. The new hours are 5 to 10 a.m. in the mornings and 3 to 7 p.m. in the evenings, Monday through Friday.

The third HOV lane for the Marin Sonoma Narrows B-7 project is scheduled to open in late September 2025.

The old HOV hours of operation on US-101 in Marin County for the southbound direction were 6:30 to 8:30 a.m. and for northbound direction, 4:30 to 7 p.m. In Sonoma County, the old hours of operation in both directions were 7 to 9 a.m. and 3 to 6 p.m.

Caltrans will be activating changeable messages signs along the entire corridor to provide information accordingly.

Motorists may experience some additional delays and increased travel times during the construction and transition period as the traveling public gets adjusted to the new hours in both counties.

HOV lanes reduce traffic by increasing vehicle occupancy as people switch to ridesharing or using transit. Carpool lanes carry more people than general purpose lanes and improve the efficiency of the freeway system. HOV operating hours are typically set to cover the periods of peak congestion and short time blocks leading up to and after those peak periods.

The HOV hours for US-101 were determined through an analysis of traffic data that was collected in the summer of 2024.

Construction for the Marin Sonoma Narrows B-7 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 the Richardson Bay Bridge near Sausalito in Marin County to Windsor in Sonoma County.

For more information about new uniform HOV lane hours, see bit.ly/3HoVfOO

Please drive with caution. Slow for the Cone Zone and Be Work Zone Alert.

For 24/7 traffic updates, please visit 511.org: https://x.com/511SFBay
For real-time information, visit Caltrans QuickMap: https://quickmap.dot.ca.gov
Follow us on X: https://x.com/CaltransD4
Or call 1-800-472-7623, 1-800-427-ROAD for state highway conditions statewide.