SM 101 Express Lanes Project

Getting More Passengers through the Busy Corridor

101 Express Lanes All Inclusive Map

Scroll down to read project information, construction updates, contact information, and frequently asked questions.

Project Information

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 on U.S. Highway 101 from I-380 in San Bruno to the San Mateo County/Santa Clara County border. The San Mateo 101 Express Lanes will then seamlessly connect to the express lanes being constructed in Santa Clara County.

SM 101 Express Lane Project How an Express Lane Operates. What is an Express Lane? Buses and 3+ carpools drive for free. Other drivers can choose to pay. Electronic toll collection. dynamic tolls (congestion pricing) keep lane free flowing.

Key Project Benefits

  • Encourages carpooling and transit use
  • Improves travel time and reliability for all express lane users
  • Increases the total number of people moved on the road
  • Uses technology to manage traffic flows
  • Reduces congestion in the corridor
  • Upgrades pavement and lane re-striping

Construction Updates

To receive construction updates, follow us on Twitter @CaltransD4 or join our mailing list by contacting Jeff Weiss. His contact information is under Contact below.

For real-time traffic information and lane closures, go to Caltrans Quickmaps.

August 2019

During the month of August, construction activities will continue along US 101 from the San Mateo County/ Santa Clara County border to US 101/ Whipple Avenue and will include lane closures on the freeway, some freeway ramps, and some local City streets next to the freeway.

Freeway Work: Intermittent lane closures will continue on northbound and southbound US 101 from 10 p.m. to 5 a.m., excluding Friday and Saturday nights. During lane closures, at least one lane will remain open at all times.

Freeway work includes:

  • installing freeway sign foundations
  • demolishing portions of the existing median barrier
  • installing new median barrier
  • installing drainage systems

Construction crews boring in freeway median to prepare for electrical connections

Ramps: Work on the freeway ramps will continue periodically for restriping and installing temporary traffic monitoring equipment. This work may require temporary, nightly ramp closures in Palo Alto and East Palo Alto. Ramp closures:

  • will be displayed on changeable message signs
  • will take place at night
  • will last 3 to 8 hours
  • will reopen by 5 a.m. daily
  • will have detour signs posted

City Streets: Electrical service work will continue to occur on City Streets in Palo Alto, East Palo Alto, Menlo Park, and Redwood City adjacent to the freeway to connect power to overhead signs and freeway lighting. This work will require temporary lane closures (one-way traffic). Lane closure(s):

  • information will be displayed on changeable message signs
  • will include traffic cones and flaggers
  • will be temporary but could occur during daytime or nighttime hours
  • could produce intermittent low vibrations and construction vehicle noise

Construction activities are subject to change.

May/June 2019

During the months of May and June, construction will continue in Palo Alto, East Palo Alto, Menlo Park, and Redwood City. Construction activities require temporary lane closures on City streets adjacent to the freeway, occasional nighttime ramp closures (select ramps only), and nighttime lane closures on U.S. 101.

Electrical service work will continue to occur on City Streets adjacent to the freeway to connect power to overhead signs and freeway lighting. This work requires temporary lane closures (one-way traffic). Lane closure(s):

  • information will be displayed on changeable message signs
  • will include traffic cones and flaggers
  • will be temporary but could occur during daytime or nighttime hours
  • could produce intermittent low vibrations and construction vehicle noise

Work on the freeway ramps will also continue periodically for restriping, and installing temporary traffic monitoring equipment.

Ramp closures:

  • will be displayed on changeable message signs
  • will take place at night
  • will last 3 to 8 hours
  • will reopen by 5 a.m. daily
  • will have detour signs posted

Ongoing freeway construction activities include:

  • demolishing portions of the existing median barrier
  • removing pavement
  • installing new median barrier
  • installing drainage systems
  • placing temporary concrete barriers on the shoulders

Lane closures occur nightly from Sunday through Thursday. Lanes will reopen by 5 a.m. daily.

April 9, 2019

Construction activities on the U.S. 101 median barrier, freeway shoulders, and ramps are ongoing in Palo Alto, East Palo Alto, Menlo Park, and Redwood City (more details in the updates below). In addition, construction activities will include electrical service work in order to power overhead signs and lighting on the freeway. Crews will be accessing existing electrical service points on local roadways adjacent to the freeway in Menlo Park, East Palo Alto, and Palo Alto. Nearby residents and travelers can expect to see crews working during the day. Traffic cones and flaggers will be used to separate vehicles from construction personnel and equipment. Temporary lane closures are anticipated to occur periodically. Lane closures are not expected to disrupt traffic circulation. Construction noise is expected to be intermittent and limited to low vibrations and construction vehicles. Work at each location is anticipated to take a few days or less.

March 22, 2019

Project construction has begun! Upcoming construction activities include placing temporary concrete barriers, demolishing portions of the existing median barrier, removing pavement, installing temporary traffic monitoring equipment, and restriping the freeway.

Over the next three months, construction activities will take place in Palo Alto, East Palo Alto, Menlo Park, and Redwood City. During this time, construction activities will occur primarily on the shoulders and median of U.S. Highway 101. Closures of select lanes on the freeway will occur nightly between 10 p.m. and 5 a.m. (excluding Friday and Saturday nights). No daytime lane closures are anticipated.

Periodic ramp closures will also occur between Palo Alto and Redwood City. Ramp closures will also occur at night and ramps would be closed 3 to 8 hours. Ramps will re-open by 5 a.m. Details regarding ramp closures will be displayed on the freeway changeable message signs. Detours will be marked.

Caltrans has constructed express lanes in other areas and found that noise associated with these activities was largely blocked by existing sound walls. Therefore, construction is expected to cause only minor noise increases. Nighttime lighting will also be used, but lights will be pointed toward the roadway to minimize impacts to nearby residents.

March 15, 2019

Project construction is starting the week of March 17, 2019. Closures of select lanes will occur nightly between 10 p.m. and 5 a.m. (excluding Friday and Saturday nights). No daytime lane closures are anticipated. Over the next three months, construction activities will take place in Palo Alto, East Palo Alto, Menlo Park, and Redwood City. During this time, construction activities will occur primarily on the shoulders and median of U.S. Highway 101.

Construction activities include placing temporary concrete barriers, demolishing portions of the existing median barrier, removing pavement, and installing temporary traffic monitoring equipment. Caltrans has constructed express lanes in other areas and found that noise associated with these activities was largely blocked by existing sound walls. Therefore, construction is expected to cause only minor noise increases. Nighttime lighting will also be used, but lights will be pointed toward the roadway.

Contact Information

To ask a question about the project, join the mailing list, talk about construction, or request a presentation for a group/organization, contact:

Jeff Weiss
Caltrans Project Public Information Officer
(510) 286-5543
jeffrey.weiss@dot.ca.gov

Frequently Asked Questions

What is an express lane?

  • Buses and 3+ carpools drive for free
  • Other drivers can choose to pay
  • Electronic toll collection
  • Dynamic tolls (congestion pricing) keeps lane free flowing

How do express lanes work?

The San Mateo 101 Express Lanes will prioritize 3+ carpools and buses by always allowing them access to the lanes at no charge. When an express lane is not full with carpools or buses, the excess capacity can be sold to other drivers willing to pay for the time advantage. The first priority in managing the lanes is to keep the traffic moving for carpools and buses. Excess capacity is only sold when it won’t harm the travel of those priority vehicles. When capacity is available, dynamic pricing is used to control the demand of paying vehicles. The more capacity that is available, the lower the price. As the express lane reaches capacity, non-priority vehicles are prohibited from traveling in the express lanes. How will the project reduce congestion?

The primary goal of the project is to move as many people as possible within the corridor. With the anticipated population growth, there is a need to implement new, innovative solutions to traffic problems. Adding express lanes provides 3+ carpools and buses with travel time savings when compared with the general purpose lanes. Selling excess capacity, when available, draws non-priority vehicles out of the general purpose lanes. This helps to reduce congestion in these lanes as well. This will move more people through the corridor without reducing the number of general purpose lanes. A more efficient freeway also encourages traffic to use the freeway instead of city streets. Express lanes also promote ridesharing, which can ultimately reduce congestion on the whole freeway.

How long will construction last?

Construction to convert the existing HOV lanes from the San Mateo County/Santa Clara County border to Whipple Avenue will begin in March 2019. Construction to add a lane from Whipple Avenue to I-380 will begin later in 2019. Construction is projected to end in 2022. During construction, every effort will be made to minimize impacts on existing traffic flow and neighboring communities.

How will construction impact me?

Construction will require nighttime lane closures on U.S. Highway 101 throughout the corridor. Working at night will minimize impacts on traffic during the day. Construction will include infrequent daytime partial-ramp closures and temporary detours to city streets. The project also includes removing and rebuilding some sound walls adjacent to northbound U.S. Highway 101 in the City of San Mateo.

How will I find out about construction activities?

All lane closures, ramp closures, and construction activities that could disrupt traffic flow will be posted to social media (i.e. Twitter: @CaltransD4) and updated on the Construction Updates page. Construction activity with the potential to affect city streets will be communicated to City and County Public Information Officers, as well.

Where can I get more information?

  • You can sign up to join our mailing list or ask a question by contacting Jeff Weiss. His contact information is listed under Contact Information.
  • You can come back to this website frequently to read construction updates.
  • You can follow us on Twitter @CaltransD4.

You can download the project fact sheet, Final Environmental Impact Report/Environmental Assessment, and other project documents at San Mateo County Transportation Authority’s documents page.