Schedule: Over the next several months, closures should be expected intermittently Monday through Friday, from midnight until 5 a.m.
Marin County — The San Rafael ramp widening project, which began in early March 2025, continues on the Northbound US-101 Bellam Boulevard off-ramp and Eastbound Interstate-580 (I-580) on-ramp.
The project, sponsored by Transportation Authority of Marin (TAM), is intended to reduce traffic congestion. During the construction phase, the off-ramp from US-101 and the on-ramp to I-580 will remain open during daytime hours; however, there will be intermittent ramp closures at night.
Periodically over the next several months, the Northbound US 101 off-ramp to Bellam Boulevard, and Eastbound I-580 on-ramp from Bellam Boulevard could be closed from midnight until about 5 a.m. for construction activities. The closures would only be on weeknights, unless announced in advance.
Detour for Northbound US-101 Bellam Boulevard off-ramp closure:
- Continue driving Northbound US-101
- Take exit 452 for Central San Rafael
- Proceed through the intersection at Second Street
- Turn left at the Traffic Light onto Third Street
- Turn left at the Traffic Light onto Hetherton Street
- Proceed onto US-101 Southbound on-ramp
- Take exit 451B for I-580 East
Detours for Eastbound I-580 on-ramp closure:
- Eastbound and westbound Bellam Boulevard traffic will be detoured to Francisco Boulevard East.
- Turn left onto Main Street, pass under the freeway.
- Turn left onto the San Quentin on-ramp to EB I-580.
- Southbound US-101 Traffic will exit at Bellam Boulevard and turn left onto Bellam.
- Turn right onto Francisco Boulevard East.
- Turn left onto Main Street, pass under the freeway.
- Turn left onto the San Quentin on-ramp to EB I-580.
No public transit impacts are anticipated. The contractor will turn on Changeable Message Signs (CMS) to notify the public ahead of time. The project will impact traffic heading onto Eastbound I-580 toward the Richmond-San Rafael Bridge.
All construction activities depend on weather. Work is ongoing and expected to conclude in winter 2025.
Please drive with caution. Please remember to Slow for the Cone Zone and Be Work Zone Alert. TAM and the County of Marin thanks motorists for their patience while we work to mitigate traffic delays in the San Rafael corridor.
The project is led by the TAM and is being conducted on state highway property, which is owned and operated by Caltrans. TAM designed and funded the project and has partnered with County of Marin Department of Public Works to administer the construction phase of the project.
- Recent news release about the construction phase
- TAM project overview webpage
- Marin County Public Works construction project webpage
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.
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