Addressing Congestion on San Francisco’s Freeways

image of SF freeway


San Francisco’s transportation system faces a critical problem: more people than ever are trying to travel to, from, and through the city. The freeways in San Francisco—US 101 and I-280—play an important role in this network, connecting San Francisco and the Peninsula.

While parts of San Francisco’s freeways are critically congested, there are many empty seats in cars, vans, and buses. And demand is expected to increase: by 2040, there will be more than 100,000 additional daily trips between San Francisco and the South Bay.

The Transportation Authority is conducting a study to understand how we can address this growing challenge. The agency’s Freeway Corridor Management Study focuses on addressing congestion while achieving the following goals:

  • Move people efficiently: We need to get more travelers to their destinations as quickly and reliably as possible in the existing freeway footprint.
  • Increase trip reliability: More reliable travel times will help everyone, from parents picking up their children from school to commuters who need to get to work on time.
  • Enhance travel choices: Better transit and incentives to carpool give commuters convenient new travel options.
  • Contribute to a regional network: San Francisco’s freeway management strategies will be coordinated with similar projects in San Mateo and across the region.
  • Reduce emissions: Moving more people in the same or fewer vehicles will help achieve our climate goals as our population grows.
  • Support community well-being: We must ensure that any changes to freeway operations support equity and safety in nearby neighborhoods.


Through this study, the Transportation Authority is investigating how our freeway lanes can be reconfigured to meet our goals.

We know that if we want to move people in fewer vehicles, we need to give carpoolers and people taking transit a time and reliability advantage. That’s why we are exploring options for dedicating one lane on portions of US 101 and I-280 for High Occupancy Vehicles (carpools and transit). Consistent with other carpool lanes in the Bay Area, these lanes could have occupancy requirements of either two or three people.

If deemed necessary, price management in the form of express lanes could also be used with either of these configurations. Express lanes are like carpool lanes that other drivers could also pay to use. Express lanes on the US 101 and I-280 would be free for eligible carpools and buses, while also being accessible to other vehicles who could pay a fee based on demand.

Carpool and express lanes are not new to the Bay Area. Carpool lanes have been in the Bay Area for more than 40 years, and express lanes have been here for 10 years.

Given the existing configuration of our freeways, carpool or express lanes could be implemented in the below segments:

Carpool or express lane segments


Right now, the Transportation Authority’s project team is gathering feedback from the community about this study, including what questions many still have about carpool and express lanes. Next, we’ll use this feedback, and continue to work with San Franciscans, travelers, and Caltrans (who owns the freeways in San Francisco), to design and evaluate a set of options and share these designs with the community.

FACT SHEET, other resources

Download the Freeway Congestion Management Study fact sheet.

Download the spring 2018 Transportation Authority Board presentation.

Download the draft Freeway Corridor Management Study Phase 2 report.


Do you have feedback on express lanes in San Francisco? Please take a few minutes to fill out this short questionnaire.


For more information, contact Andrew Heidel, Senior Transportation Planner, at (415) 522-4803 or via email.

The SF Freeway Corridor Management Study is funded by Caltrans and the Prop K half-cent sales tax for transportation.


Top photo courtesy Sergio Ruiz.