SAN MATEO, Calif. (KRON) — The full San Mateo 101 Express Lanes corridor is now open and operational, transportation officials announced on Friday.

The new express lanes stretch along 22 miles in each direction of Highway 101, from the San Mateo County/Santa Clara County Line to Insterstate-380 in South San Francisco.

All motorists that use the express lanes must have a FasTrak account with a FasTrak Flex toll tag, or FasTrak Clean Air Vehicle toll tag displayed in the vehicle. Those without FasTrak toll tags will be in violation and are subject to fines and penalties.

The $581-million San Mateo 101 Express Lanes Project is one of the largest public/private infrastructure partnerships in San Francisco Bay Area history.

“The U.S. 101 corridor is a critical trade and commute route running through the Peninsula connecting San Francisco and Silicon Valley. The region continues to experience significant economic growth resulting in increased congestion on U.S. 101,” said Rico Medina, Chair for the San Mateo County Express Lanes Joint Powers Authority.

“The fully operational express lanes are a new mobility option that will help reduce traffic congestion, provide more reliable travel times, encourage carpooling and transit use, and provide funding for equity programs for all users of U.S. 101 in San Mateo County,” Medina said.

The lanes will operate from 5 a.m. to 8 p.m. weekdays. The cost to access the lanes will be displayed on electronic overhead signs so motorists will know the cost prior to entering the express lanes.

“The added 22 miles of express lanes will provide many benefits to the region and the use of modern technology to manage traffic will aid in reducing congestion in the corridor,” said Alicia Aguirre, Vice Chair for the SMCEL-JPA.

For more information about FasTrak or to purchase a toll tag, .

The construction of the San Mateo 101 Express Lanes was completed in two phases. The first phase from San Mateo County/Santa Clara County line to Whipple Avenue opened to traffic last year in February 2022.  

Caltrans managed the design and construction of the San Mateo 101 Express Lanes.

Dina El-Tawansy, Caltrans District 4 Director, said, “With funding from the state’s Senate Bill 1 program, the region, the county and major businesses, these lanes will help improve the quality of life, promote carpooling and transit and enhance equity and access for all Californians who travel this vital corridor.”

The San Mateo 101 Express Lanes now seamlessly connect to express lanes in Santa Clara County.