TransForm's new report proposes way to reduce traffic on Highway 101 in San Mateo County

Jeff Hobson head shot

San Mateo County has a traffic problem. And if we don’t pursue innovative solutions, traffic will get worse. 

In addition to crushing gridlock on Highway 101, alternatives like Caltrain are overcrowded, and employer shuttles that daily carry thousands of commuters to companies like Google and Genentech are caught in the same crawl as people driving alone. 

That’s why TransForm is proposing that San Mateo County study an innovative strategy for express lanes that will make the best use of highway lanes and simultaneously fund transportation choices to truly reduce congestion. Express lanes, also known as “high-occupancy toll” or HOT lanes, allow solo drivers to access carpool lanes by paying a fee when the carpool lanes aren’t full. (Read more background on express lanes here and here.)

Our new report, Innovation Required: Moving More People with Less Traffic, shows that a new approach we’re calling “Optimized HOT” would move nearly twice as many people as the county’s current proposal, but have less traffic for everyone.

The county has proposed spending approximately $150180 million to construct a new carpool lane on Highway 101. However, according to the report, the conventional highway expansion approach will only result in worse traffic in the future, at high cost to taxpayers.

In contrast, the Optimized HOT scenario would cost just $18 million to convert an existing lane of Highway 101 into an express lane. Instead of paying for pavement, San Mateo County could invest in better, faster transportation overall, sharing the benefits more widely among commuters, taxpayers, and the environment.

A critical component of Optimized HOT is ensuring that up-front costs to construct an express lane are low, so that revenues can be used to fund express buses, vanpools, and other transportation options that benefit commuters of all income levels. If the county just builds a carpool lane, and high construction costs mean that no express lane revenues are used to support alternatives to driving, only drivers who can afford to use the new highway lanes will gain advantages. Optimized HOT would spread the benefits more equitably to all commuters.

The infographic above offers a snapshot of the different scenarios analyzed in the report.

Click here for a larger web version of the infographic.

Benefits of Optimized HOT include:

  • Nearly twice as many people traveling the 101 corridor per hour
  • Lower up-front costs: $18 million vs. $150180 million
  • Quicker construction completion to begin collecting revenues
  • Fewer vehicles per hour, leading to reduced pollution
  • Funds available to provide transportation options for more people of all income levels

Since Optimized HOT has so much to offer, we’re recommending study of this scenario, both in San Mateo County and throughout the Bay Area. Regional agencies are planning an express lane network that will include 550 miles of express lanes throughout the Bay Area. San Mateo County could lead a new approach to congestion management – if an antiquated state policy is changed to clear the way.

Currently, California law prohibits conversion of an existing highway lane into an express lane. We think it’s time that these outdated state restrictions be lifted, at least to allow evaluation through a few demonstration projects.

We’ll be working in the new year to build support for changing state policy and incorporating the Optimized HOT strategy into plans for the region’s express lane network. 

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About This Blog

TransForum is the blog of TransForm, California's leading transportation advocate. For more about our work, including ways you can take action and contribute, visit