The Express Lanes project in San Mateo County will not only cause Highway 101 lane and ramp closures over the next two-plus years, but also full freeway and local road closures. 

All Highway 101 lanes in one direction in the county will shut down 12 times next year between midnight and 5 a.m., causing detours, Caltrans consultant Leo Scott said during a C/CAG meeting Thursday. That’s so crews can take down and put up new signs on each of the six sign bridges on the corridor. 

Motorists should also expect daytime local street closures through mid-2022, though they will be “fairly minor,” Scott said. Street closures will be necessary when crews remove and reconstruct sound walls, relocate sewer lines and work on utilities, which starts this month and in March. 

During those months, crews will begin relocating the sewer line around the Dore Avenue off-ramp and demolishing the sound wall between Newbridge Avenue and Beacon Avenue in San Mateo as well as removing vegetation and the existing concrete barrier.

The vast majority of construction work will occur at night, between Sunday and Thursday from 9 p.m. to 6 a.m. Delays are expected to be between 15 and 25 minutes or even longer at any given time in that window, though congestion due to construction is expected to be minimal after 1:30 a.m., Scott said. 

“Our goal is to avoid delays before 9 p.m. and after 6 a.m.,” Scott said. “Most congestion will occur between 9 p.m. and 1 a.m.” 

Highway 101 ramp and lane closures will be at night and Consecutive ramps will not be shut down at the same time and there will always be a detour to the next ramp when the nearest one is closed.

During construction, Caltrans will be sending out weekly email updates about closures and anyone can sign up at or at

Real-time traffic signs will be installed roughly every mile throughout the corridor to notify motorists where the slowdown begins.

Caltrans has and will be working with communities whose residents commute to San Mateo County as well as large employers so their employees are aware of the project. SFO will also be notifying passengers about the project and traffic impacts.

Several board members are worried about congestion on local streets due to commuters jumping on and off Highway 101 to avoid backups there. Scott said Caltrans has reached out to navigation apps including Waze and asked them not to send commuters to local streets when congestion is bad, though that app specifically said there’s nothing it can do as information related to anticipated closures is entered into the Waze system by its users. 

The $580 million project will construct a new lane in each direction of the highway between the Whipple Avenue exit in Redwood City and Interstate 380 in South San Francisco. 

The far left lane in each direction will be converted to an express lane, on which buses and carpools of three or more people can travel for free while solo drivers will have to pay a toll that fluctuates based on traffic volumes. Tolls are expected to be between 50 cents and $1 per mile on average and no more than $3 per mile, and they’ll be paid via a FasTrak transponder, according to Caltrans. 

An equity program offering discounts to low-income motorists could be offered once the express lanes are open.

Officials say users of the new express lanes will be able to travel at least 45 mph at all times and the plan is to also roll out a series of express bus routes to travel on those lanes. SamTrans has already debuted one such route called the FCX, which connects Foster City to San Francisco. It’s one of six express bus routes that will be rolled out in the coming years. 

The first phase of the project, which is wrapping up now, converted the existing carpool lanes between the Whipple Avenue exit and the Santa Clara County line into express lanes. The work entailed sign installation and restriping, among other tasks. 

The San Mateo County express lanes are expected to open late 2022, and the plan is to eventually extend the express lanes so they travel between San Francisco and San Jose.

In other business, the C/CAG board Thursday advanced to the environmental review phase a project that will extend the express lanes from the Interstate 380/Highway 101 interchange to the San Francisco County line. 

During the meeting, the board also signed off on a series of short-term improvements for the State Route 92/Highway 101 interchange aimed at reducing weaving conflicts and improving safety. Construction is expected to begin in 2023. Long-term improvements aimed at increasing capacity and reducing congestion on the interchange are expected to break ground in 2024 and be complete in 2027.

(650) 344-5200 ext. 102

Recommended for you

(0) comments

Welcome to the discussion.

Keep it Clean. Please avoid obscene, vulgar, lewd, racist or sexually-oriented language.
Don't Threaten. Threats of harming another person will not be tolerated.
Be Truthful. Don't knowingly lie about anyone or anything.
Be Nice. No racism, sexism or any sort of -ism that is degrading to another person.
Be Proactive. Use the 'Report' link on each comment to let us know of abusive posts.
Share with Us. We'd love to hear eyewitness accounts, the history behind an article.