Carpooling for Cash and Congestion-clearing

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Mineta Transportation Institute finds that $15 a day would incentivize commuters to accept the minor inconveniences of carpooling
July 29, 2020
San José, CA

New case-study research from the Mineta Transportation Institute finds that $15 a day would incentivize commuters to accept the minor inconveniences of carpooling, and as documented in the report Congestion-clearing Payments to Passengers (CCPTP), incentivized carpooling could reduce traffic congestion by as much as half. 

Traffic congestion is clearly linked to negative environmental impacts, economic drawbacks, and a reduced quality of life; yet many commuters are reluctant to alter their traditional driving habits in favor of carpooling. However, this case study, based on a long-standing bottleneck location on Highway 92 in Half Moon Bay, California, found that at $15 a day, half of people driving on a busy road would be willing to travel as passengers and another 23% would be willing to serve as drivers.

Additional findings from this case study revealed that: 

  • The removal of peak-hour congestion could create a new preferred travel time for single occupancy vehicles (SOV).

  • Traffic reduction efforts are potentially limited by commuters’ willingness to serve in different carpool roles (e.g. driver, passenger, or both). 

  • There is a need for a combination of incentives: first to shift drivers to passengers, and, second, to encourage passengers to travel earlier (or later) than their preferred travel time to match that of the potential driver.

  • There is a potential need for meeting-place-based parking near bottlenecks to simplify higher occupancy vehicle formation whether in bus, van, or car.

This case study also provides a method for estimating the cost and benefits of a permanent program, removing congestion by paying people to travel as passengers. Furthermore, the project team proposes a pilot project on the case study route at a cost of $40 million over five years with a potential savings in years 3-5 after an initial learning curve.

Principal investigator on the project, Paul Minett, explains how “The potential value of this solution, if it works as well with real commuters on congested roads as it does in the planning spreadsheets of this project, is many multiples of this investment both nationwide and worldwide.” 

While the long-term impacts of COVID-19 are still being assessed, the project team foresees two trends that may impact traffic congestion--reduced use of public and shared transport due to virus transmission concerns and a reduction in commuter traffic as employees continue to work from home. “The net effect is difficult to predict because there might be lasting damage to economies depending on how long the disruption of COVID-19 continues,” says report co-author John Niles. “Either way, the aftermath will be an ideal time to test CCPTP and could offset financial losses from the disruption caused by COVID-19 by redistributing funds to people; and encourage, as soon as is appropriate, a return to shared transport as a mechanism for managing congestion,” he adds.  


At the Mineta Transportation Institute (MTI) at San Jose State University (SJSU) our mission is to increase mobility for all by improving the safety, efficiency, accessibility, and convenience of our nations’ transportation system. Through research, education, workforce development and technology transfer, we help create a connected world. MTI was founded in 1991 and is funded through the US Departments of Transportation and Homeland Security, the California Department of Transportation, and public and private grants. MTI is affiliated with SJSU’s Lucas College and Graduate School of Business.


Paul Minett is an MTI Research Associate, managing director of Trip Convergence Ltd., and chief executive of Strategic Lift Ltd., a strategy consultancy providing advice to small and medium sized businesses. John Niles is an MTI Research Associate and Founder and President of Global Telematics, a policy research consultancy based in Seattle focused on designing policies and actions for transportation improvement. Dr. Richard Lee is an MTI Research Associate and lecturer in the Urban and Regional Planning Department at San José State University and a Principal with Transportation Choices for Sustainable Communities, a non-profit research and policy institute. Brittany Bogue is an MTI Research Assistant and graduate student in Urban and Regional Planning at San Jose State University. Her research interests broadly include sustainable transportation and mobility justice.


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