Transportation Partners Announce New HOV Lane Hours In Marin, Sonoma Counties For 2026

Marin County and Sonoma County - Transportation partners Caltrans, the Metropolitan Transportation Commission (MTC), the Transportation Authority of Marin (TAM) and Sonoma County Transportation and Climate Authorities (SCTCA) announced adjustments today affecting High Occupancy Vehicle (HOV) hours on US-101 in Marin and Sonoma counties.

New HOV hours will take effect in late February (weather permitting) and operate between 6 a.m. to 9 a.m. in the mornings and 3 p.m. to 6:30 p.m. in the evenings, Monday through Friday. The hours are based on Caltrans traffic analysis along the corridor that was completed this month. The new hours will begin after updates are made to HOV hours signage. Signs will be updated along the entire length of the HOV lanes, stretching from the Richardson Bay Bridge in Marin County and Windsor in Sonoma County.

With this decision, the transportation partners remain committed to providing carpool lanes and encouraging transit in the North Bay while helping to relieve congestion on the US-101 corridor.

Though the change to the US-101 HOV hours of operation in September 2025 led to some congestion and delays, additional factors also appear to have contributed to traffic impacts, including elimination of clean-air vehicle access. To address this, Caltrans completed its traffic monitoring timeframe ahead of schedule, from Spring 2026 to January, to accommodate more immediate changes to the HOV hours.

The new hours will continue to be consistent in Marin and Sonoma counties and will cover a majority of the peak commute hours in both directions in the morning and afternoon/evening.

The current HOV lane hours in both counties are 5 a.m. to 10 a.m. in the mornings and 3 p.m. to 7 p.m. in the evenings, Monday through Friday.

As part of broader transportation management efforts, Caltrans (in partnership with its transportation partners) activated nine ramp meters along northbound and southbound US-101 in Marin and Sonoma counties on Tuesday, Dec. 2. More ramp metering is scheduled to be activated along the corridor as construction activities are completed in the field.

With the completion of the three-lane configuration in the Marin Sonoma Narrows project in 2025, there are now 52 miles of continuous carpool lanes in each direction of US-101. The new HOV lanes account for the second longest in California.

Carpool lanes move more people in fewer vehicles and encourage carpools and transit options to improve freeway efficiency and traffic flow.

Caltrans and MTC will continue to monitor traffic conditions on the freeway using traffic cameras, vehicle detection stations, and other sources. The department is analyzing various datasets - including travel times, speeds and congestion duration, transit travel times and ridership statistics, corridor traffic volumes, HOV lane utilization, roadway incidents, and freeway service patrol response.

For more information about the current HOV lane hours, see bit.ly/3HoVfOO.

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For real-time information, visit Caltrans QuickMap: https://quickmap.dot.ca.gov
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Or call 1-800-472-7623, 1-800-427-ROAD for state highway conditions statewide.