Project Design/General Questions
The San Mateo 101 Express Lanes Project is a multi-year, multi-agency project initiated to reduce traffic congestion and encourage carpooling and transit use on U.S. 101 in San Mateo County. The project will create 22 miles of express lanes in each direction on U.S. 101 from I-380 in South San Francisco to the San Mateo County/Santa Clara County line. The San Mateo Express Lanes will then seamlessly connect to the express lanes being constructed in Santa Clara County. When the project is complete, drivers will be able to drive in an express lane from the southern end of Sunnyvale to the San Francisco airport.
2. How will the express lanes work and will they improve traffic?
Express lanes are High Occupancy Vehicle (HOV), or carpool lanes, with the option for non-carpoolers to pay a toll to use the lanes when space is available. When non-carpoolers enter the express lanes, they free up space in the other freeway lanes reducing overall congestion.
The express lanes are designed to work as follows: vehicles with 3 or more persons will be exempt from tolls, this includes carpools and buses. Vehicles with two people in them and vehicles with active Clean Air Vehicle decals will have the option to enter the express lane and pay a reduced toll. Solo drivers will have the option to enter the express lane and pay the full toll displayed at the time of entry into the lane.
The express lane operator will use dynamic pricing to optimize the performance of the lane, maximizing the movement of people through the corridor. The operator will monitor the freeway and raise or lower the toll as necessary to keep traffic flowing in the express lanes.
When the operator sees the express lane slowing down as a result of too much traffic, the toll price is increased for those who paid to be in the lane. This reduces the willingness of non- 3+ carpoolers to enter the lane, freeing up capacity in the express lane and making it easier for carpoolers and buses to travel faster. The operator will also have the option of limiting the express lane to only 3+ carpoolers, buses, and other multi-occupancy vehicles if traffic in the lane becomes too slow. Non-3+ carpoolers will need to exit the HOV lane.
During the hours of operation, these lanes are planned to enable traffic to travel at speeds of 45 miles an hour or greater per Federal Highway Administration (FHWA) requirements. When the lanes drop below that speed the toll operator may take corrective actions.
3. Who decides how much the tolls will cost?
Who decides how much the tolls will cost? The price for tolls has not been set yet. A six-member governing body made up of the San Mateo County Express Lanes Joint Powers Authority (SMCEL JPA), three San Mateo County Transportation Authority (SMCTA) Board members and three City/County Association of Governments of San Mateo County (C/CAG) Board members will make all policy decisions. This includes setting toll policies and prices. Board meeting material and information is available here
4. How will the project benefit transit users?
Express lanes improve travel time and reliability on bus service by minimizing the delays caused by sitting in traffic. SamTrans (the San Mateo County bus service) is planning multiple express bus routes
5. Does this project take away a lane on U.S. 101?
The existing number of general-purpose through lanes will stay the same. Through extensive study, engineers determined they could fit an express lane in each direction by reconfiguring existing lanes and using space from shoulders, without taking away a through lane on U.S. 101. This will result in one new express lane in either direction along with the existing general-purpose lanes.
6. Will there be a shoulder to pull over on once the lane is constructed?
The project will maintain shoulders, but the widths may be reduced in areas due to right of way constraints.
7. Are toll lanes fair for lower income drivers?
The SMCEL JPA will be conducting a study to assess the equity needs, including those of the lower income community, in the U.S. 101 express lanes project area. The study is slated to begin spring 2020 and will take approximately 12 months to complete. The SMCEL JPA will then consider recommendations and/or strategies that result from the study.
8. Why not just build a carpool lane?
Caltrans traffic engineers studied a variety of options to determine the most effective way to move people on the U.S. 101 corridor in San Mateo County. They found that with the existing number of two-person vehicles (or 2+) driving on the corridor, a 2+ carpool lane would fill up quickly and be congested. This would eliminate the benefits for transit riders and 2+ carpoolers. However, the traffic analysis projected that a 3+ carpool lane would accommodate the existing 3+ carpoolers and contain extra space. Combining a 3+ carpool lane with dynamic pricing for other vehicles (single occupancy, dual occupancy, and clean air vehicles) allows the express lane to maintain a consistent speed while also improving travel time for the remaining lanes. Therefore, it proved to be the most effective way to move people on the U.S. 101 corridor in San Mateo County.
9. Why is the project being built here in San Mateo County?
Industries along the U.S. 101 corridor produce between 20-25% of California’s annual gross domestic product. This booming economy has fueled revenue and job growth, but it has also created overcrowding on U.S. 101, the major commute route between San Francisco and Silicon Valley. The San Mateo 101 Express Lanes Project will create 22 miles of express lanes in each direction between I- 380 and the San Mateo County/Santa Clara County line.
10. How will the express lanes in San Mateo County connect to the ones in Santa Clara County? Will I have to pay twice?
The SMCEL JPA will determine toll policies and prices. Tolls will be based on zones within the corridor and paid using FasTrak
®. Each zone is approximately 4-5 miles long and a specific toll price will be assigned to travel in that zone. Tolls will accumulate as you travel through multiple zones on a trip. Overhead message signs give drivers advance notice of a price to travel to a specific destination in the toll lane. People in the express lane will experience no difference as they travel from one county to another.
11. What happens to the tolls collected?
Revenue from the tolls can go to a variety of places and will be decided by the SMCEL JPA. Revenues must first be used to cover the operating and maintenance cost of the express lanes. In accordance with state and federal regulations, funds in excess of what is needed for the operations of the lanes can be used on transportation corridor improvements, the improvement of transit service, and support for transit operations, such as:
- Increased transit services
- Park & ride lots
- Transit signal priorities
- Offset for potential equity and incentive programs
- Local improvements such as first & last mile projects to support transit operations
- Expansion of express lanes north of I-380
The SMCEL JPA is developing an expenditure plan to help determine the best uses of these revenues.
12. How is the project funded?
This project is fully funded. The $581 million project is funded through a combination of Federal, State, local, regional and private contributions. With over $53 million pledged from the private sector, this is one of the largest public/private infrastructure partnerships in the history of the region. Additional funds include $9.5 million in federal funding and nearly $307 million in state funding.
13. Why doesn’t this project extend all the way to San Francisco?
SMCTA and C/CAG are working with the San Francisco County Transportation Authority (SFCTA) to explore and evaluate options to extend the express lane from I-380 to San Francisco.
Project Management and Operations
14. Who owns this project and is responsible for deciding operations policy?
The San Mateo County Transportation Authority (SMCTA) and the City/County Association of Governments of San Mateo County (C/CAG) have formed the San Mateo County Express Lanes Joint Powers Authority (SMCEL JPA) to own the express lanes. The SMCEL JPA will be responsible for setting policies for operations of the express lanes. More information about the JPA
can be found at http://ccag.ca.gov/express-lane-jpa/
15. Who is managing this project?
Project design and construction is being managed by an integrated team from the California Department of Transportation (Caltrans), the San Mateo County Transportation Authority (SMCTA) and the City/County Association of Governments of San Mateo County (C/CAG).
16. Who will operate the express lanes?
Bay Area Infrastructure Financing Authority (BAIFA), a Joint Powers Authority between the Metropolitan Transportation Commission (MTC) and the Bay Area Toll Authority (BATA), will operate the express lanes under contract by the SMCEL JPA.
Using the Express Lanes
17. How do I pay for the express lane?
All vehicles wishing to use the San Mateo express lanes must have a valid FasTrak Flex® toll tag to receive a discounted or toll-free trip. If you have an older FasTrak tag, it needs to be upgraded to the new Flex version which allows drivers to set the tag to a 1, 2 or 3+ occupancy. For more information visit the website
18. Who will be able to use the express lanes?
The express lanes were designed to prioritize 3+ carpools and buses, however, the SMCEL JPA will officially determine who is eligible to use the lanes and when.
19. If I don’t want to pay a toll, what are my options travelling on U.S. 101?
Consider transit or carpooling. Since express lanes are designed for transit vehicles and carpools with 3 or more people, they provide faster and more reliable travel times for transit users and vehicles with 3 or more people. In addition, express lanes are voluntary, and U.S. 101 in San Mateo County will continue to have the same number of general-purpose lanes that exist today. No one will be forced to pay a toll to drive on U.S. 101.
20. How are toll prices determined in real time?
Express lanes are a technology driven strategy to manage traffic congestion and maximize the performance of the corridor (increase person throughput). Traffic conditions are constantly monitored through detectors in the roadway, feeding that information back to the traffic control center. When traffic in the lane is regularly above 45 mph, more non 3+ occupancy vehicles are enticed into the lane by lowering tolls. When the flow of traffic in the lane falls below45 mph, non 3+ occupancy vehicles entering the express lane are automatically controlled through pricing by algorithms. The lane can even go into an “HOV Only” mode if needed. This helps maintain the minimum speed in the lane at 45 mph or above.
Overhead message signs give drivers advance notice of a price to travel to a specific destination in the express lane.
21. How are occupancy rules enforced in the express lanes?
California Highway Patrol (CHP) is responsible for enforcement. There are several CHP enforcement areas along the project corridor. Since all express lane users are required to us.
CHP officers can monitor the occupancy of each vehicle. FasTrak Flex® toll tags set at “2” or “3+” will trigger beacons that help CHP officers enforce occupancy requirements in the lanes. In addition, cameras will be able to photograph license plates of vehicles that use the lanes without a toll tag for toll violation enforcement. Video surveillance will allow FasTrak® to identify possible toll evaders with license plate reader technology, like the video technology already in use on Bay Area bridges. This technology is being expanded across Bay Area Express Lanes to provide consistency for its users.
22. How does FasTrak work with the express lanes?
Before starting a trip, solo drivers must set their FasTrak Flex® toll tag to the “1” position so the toll system can charge the vehicle the proper toll. A carpool driver with one passenger (for a total of 2 in the car) would set the toll tag to the “2” position to get a toll discount. Cars with a valid Clean Air Vehicle decal wishing to get a discount would also set it to 2. Carpool drivers with 3 or more passengers or motorcyclists must set their toll tag to the “3+” position. The “2” and “3+” settings allow eligible vehicles to use the lanes toll-free or for discounted tolls. These toll tag settings also trigger beacons that help CHP officers enforce vehicle occupancy requirements.
23. What if there is an accident and the only open lane is the express lane?
CHP will take over and have complete control over the system in the event of an accident. The lane will be opened or closed to various vehicles at their discretion.
24. Where can I find more information on how this project fits into the larger network of Bay Area Express Lanes?
25. What will the hours of operation for express lanes be?
At the time of opening, the operation hours will be 5AM to 8PM, Monday through Friday.
26. How long will it take to build?
Construction began in 2019 in Palo Alto, East Palo Alto, Menlo Park, and Redwood City. Construction in San Carlos, Belmont, San Mateo, Burlingame, Millbrae, San Bruno, and South San Francisco will begin in early 2020. All construction is projected to end in late 2022. During construction, every effort will be made to minimize adverse impacts to the neighboring communities and the traveling public. The best way to stay informed is to sign up for the weekly construction update or quarterly project update by emailing
with the subject line “weekly” or “quarterly” to email@example.com or visit the 101 Express website
27. How will construction impact me?
The following types of construction impacts are anticipated:
- Nighttime lane closures on U.S. 101 throughout the corridor. Working at night will minimize impacts on traffic during the day. Closures could occur from 9PM to 5:30AM Sunday through Thursday. Significant traffic delays are expected to occur between Grand Avenue and Holly Street from 9PM and 1AM.
Infrequent ramp closures and temporary detours to city streets.
- Temporary lane closures on city streets adjacent to the freeway causing one-way traffic to connect electrical components to nearby hook-ups.
- Removing and rebuilding some sound walls adjacent to northbound U.S. 101 in the City of San Mateo. To check if sound wall construction will be near your home, view the video here.
- Utility relocation (in conjunction with sound wall work in San Mateo).
- Vegetation removal adjacent to the freeway.
- Six overnight full freeway closures in 2021. These closures will take place in only one location per direction at a time and will have a detour plan in place.
Details about when each impact will occur will be included in weekly construction updates. These updates will be posted to the project website at 101express.com.You can also sign up to receive the weekly construction updates by emailing
with the subject line “weekly” to firstname.lastname@example.org.
28. How can I find out about construction activities that may affect traffic?
In addition to the weekly construction updates, Caltrans will provide up-to-date traffic and closure information on portable message signs by the side of the road. Construction activities that could disrupt traffic flow will also be communicated to the general public directly via social media (i.e. Twitter: @CaltransD4
) and electronic communications (i.e. e-mail and website). Commuters are encouraged to stay informed by signing up for weekly construction updates by emailing
with the subject line “weekly” to email@example.com or by visiting the 101 Express website
Any construction activity with the potential to affect city streets will be communicated directly to city staff as well as to the general public directly via social media and electronic communications. General project updates will be communicated to city staff quarterly.
29. Where can I get more information about the San Mateo 101 Express Lanes Project?
Caltrans maintains a project website
at 101express.com. Anyone can visit the website and sign up to receive weekly construction updates on the San Mateo 101 Express Lanes project by joining the mailing list. Follow @CaltransD4 on Twitter
for the most up-to date information.
30. Why is construction occurring from 9PM-5:30AM?
Caltrans, SMCTA and C/CAG want to make the most efficient use of public and private funds. Working from 9PM to 5:30AM aims to reduce the duration of the project, bringing much needed congestion relief to the corridor sooner and saving six months and $40 million dollars over a 10PM start time, which was the start time for the southern phase. The 9PM to 5:30AM construction window provides crews a meaningful block of time to conduct various construction activates when traffic volumes are at the lowest levels.