101 Express Lanes Overnight Closures

Additional Overnight Closures on U.S. 101 – Fall 2021

As part of the San Mateo 101 Express Lanes Project, Caltrans will be replacing a total of six overhead sign structures (that span the width of one side of the freeway, from the shoulder to the median) on U.S. 101. The first step of this work is to safely remove the sign structures and install temporary orange roadside signs along the freeway shoulder. Due to the large size of these sign structures, it is necessary to close one direction of the freeway at a time.

Caltrans completed the removal of all six overhead sign structures and installed temporary orange roadside signs along the freeway shoulder on U.S. 101. This work required construction crews to close one direction of the freeway at a time between Millbrae Avenue in the City of Millbrae and South Airport Boulevard in the City of South San Francisco for five nights, and northbound U.S. 101 between East Hillsdale Boulevard and SR-92 in/near the cities of San Mateo and Foster City for one night. Additional freeway closures will be required in Fall 2021 to install new overhead sign structures at the above locations. See “Additional Freeway Closures This Fall” below. 

Sign structures are being replaced to make room for the new express lanes throughout the corridor. 

highway sign across highway 101

Additional Freeway Closures This Fall

To install new sign structures, where sign structures were removed, additional freeway closures will need to occur. Closures of the below sections of freeway are currently scheduled to occur in Fall 2021. Updated closure information will be posted on this page when available and will also be distributed through our weekly construction email. 

  • Northbound U.S. 101 from Millbrae Avenue to San Bruno Avenue
  • Southbound U.S. 101 from San Mateo Avenue to San Bruno Avenue
  • Northbound U.S. 101 from East Hillsdale Boulevard to SR-92

Learn More

Check out the Project’s video on the freeway closures and detour routes. Click here to watch video!
Access real-time traffic conditions on the Caltrans QuickMap: quickmap.dot.ca.gov
Sign up for weekly updates by emailing with the subject line “weekly” to 101express@dot.ca.gov
Follow @CaltransD4 on Twitter for the most up to date information on freeway closures and other construction activities planned each week. 

photo of crane lifting 101 sign structure | photo of mounted 101 sign structure