1. Home
  2. Caltrans Near Me
  3. District 4
  4. What You Need to Know
  5. New Ramp Metering Activation Scheduled to Begin December 2 on US-101 On-Ramps in Marin and Sonoma Counties

New Ramp Metering Activation Scheduled to Begin December 2 on US-101 On-Ramps in Marin and Sonoma Counties

Published:

Operating Days: Mondays through Fridays; see times below

District 4 Caltrans Logo and Building California Logo

Marin and Sonoma Counties — Caltrans, in partnership with Metropolitan Transportation Commission (MTC), the Transportation Authority of Marin (TAM), and Sonoma County Transportation and Climate Authorities (SCTCA), is scheduled to activate 12 specific ramp meters along northbound and southbound US-101 in Marin and Sonoma counties starting Tuesday, Dec. 2. Activations will occur in sequence as each location becomes ready.

Black and white highway shield for U.S. Highway 101.Ramp meters will be activated at the following on-ramps:

Sonoma County Northbound US-101

  • North Old Redwood Highway/Petaluma Boulevard loop on-ramp
  • North Old Redwood Highway diagonal on-ramp

Sonoma County Southbound US-101

  • Kastania Road/S. Petaluma Boulevard diagonal on-ramp
  • Lakeville Street/Caulfield Lane hook on-ramp
  • E. Washington Street diagonal on-ramp
  • N Petaluma Blvd/N Old Redwood Hwy hook on-ramp
  • Old Redwood Hwy / N Petaluma Blvd loop on-ramp

Marin County Northbound US-101

  • Shoreline Highway/Almonte Boulevard hook on-ramp
  • Redwood Highway Frontage Road/De Silva Drive hook on-ramp

Marin County Southbound US-101

  • De Long Avenue diagonal on-ramp
  • Atherton Avenue diagonal on-ramp
  • San Antonio Road/Redwood Sanitary Landfill Road diagonal on-ramp

These ramp meters are located in the cities of Petaluma, Novato, Sausalito, and Mill Valley, where the meters are ready for activation. These metering signals will operate Mondays through Fridays.

Operating Hours:

Sonoma County Northbound:

  • Mondays through Fridays from 6 a.m. to 10 a.m. and 3 p.m. to 7 p.m.

Sonoma County Southbound:

  • Mondays through Fridays from 6 a.m. to 10 a.m. and 3 p.m. to 7 p.m.

Marin County Northbound:

  • Mondays through Fridays from 2 p.m. to 7 p.m.

Marin County Southbound:

  • Mondays through Fridays from 5 a.m. to 11 a.m.

The De Long Avenue, Atherton Avenue and San Antonio ramps currently are in the Marin Sonoma Narrows B7 project area, so ramp metering will be active sometime in early 2026 after work has finished.

Ramp metering operations will help reduce traffic congestion and delays, enhance safety, and improve the efficiency and reliability of commuter travel along the corridor.

This activation is part of the ongoing ramp metering initiative planned for US-101 in Marin and Sonoma counties. As additional funding becomes available, more ramp meters will be implemented in both directions.

For inquiries related to Caltrans’ ramp-metering activation, please call (510) 286-4531.

What to expect?

During ramp metering hours at the specific on-ramps, motorists will encounter active ramp metering signals that cycle to manage vehicle flow. Advance warning signs at these metered on-ramps will also be activated simultaneously to alert drivers.

What Is ramp metering?

Ramp metering is a proven traffic management strategy that uses traffic signals on freeway on-ramps to control the rate at which vehicles enter the freeway. By creating room between vehicles, ramp meters reduce congestion, enhance safety, and improve overall traffic flow.

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.