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U.S. 101 San Mateo County Ramp Metering Project SM/SF County Line to State Route 92

Metering Photo

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Traffic & Updates

The Project

Caltrans and its project partners City County Association of Governments of San Mateo County (C/CAG), and Metropolitan Transportation Commission (MTC) are working together on improving operations on U.S. Route 101 in San Mateo County. The improvements include the installation and activation of ramp meters at various locations.


Ramp metering is a traffic management strategy using traffic signals and accompanying equipment and techniques to improve flow on the freeway system by managing the on-ramps. Caltrans expects the ramp metering system to improve safety and travel times during the peak periods of heavy traffic along the corridor.

What to Expect

Ramp metering will begin in the Southbound direction of U.S. Route 101 in San Mateo County at 17 locations from San Mateo/San Francisco County line to State Route 92 in San Mateo.

April 28, 2015, ramp meters will be activated, but meters will rest in green. May 5, 2015, ramp meters will start cycling (or metering) during Southbound PM peak time from 2:30pm to 8:00pm. May 12, 2015, ramp meters will start cycling during Southbound AM peak time from 6:00am to 10:00am.

Most ramps will operate at “1 car per green” except for one freeway to freeway connector ramp which will meter and operate at “2 cars per green”. The one freeway connector is the Eastbound State Route 92 to Southbound U.S. 101 Connector.

Following activation, Caltrans will monitor ramp metering vehicle activity and optimize systems as needed. In addition, ramp meters could be subject to time changes based on monitoring results.