Carpool Incentives Exposed

Today, I read an interesting study about incentives. The Carpool Incentive Program Demonstration Project Study, outlines the results of various carpool incentive programs and shows how cash can really induce transportation mode shifts.

One of the most interesting programs was the Los Angeles Rideshare Rewards program, where “The Rideshare Rewards Program provided $2 per day for up to 3 months…in the form of gift certificates to new ridesharers.” This program seemed very successful and results are in the graph below. What was most interesting was the huge mode shift and decent retention rates after the program was finished.

But overall, the full analysis relies upon a previous study, Suburban attitudes toward policies aimed at reducing solo driving, to call out that incentives work better than disincentives. Not so fast though! Within that study it noted its own limitation: “A possible limitation of our approach could be that the stated preferences of solo drivers might not really reflect the actual behavioral change that will take place. However, the social psychology literature indicates there is a strong link between stated intentions and actual behavior…”(Baldassare)

While this may sound like a credible view, I disagree. In other studies where people were surveyed as in this study, many people that indicate willingness to change their behavior do not. For example, after people in one study indicated an interest in carpooling, they were sent carpool matching lists to form carpools. “Up to half of the people who originally indicated an interest in carpooling, indicated in a follow-up survey that they really were not interested in carpooling. The reasons for not carpooling were numerous and probably typical.”(Dueker 689)


1. Rogers, Jonathan. Nicholas Ramfos, and Dalvamani Sivasailam. National Capital Region Transportaiton Planning Board (TPB) Commuter Connections Carpool Incentive Demonstration Project Study. January 27, 2009.

2. Dueker, Kenneth, J. Brent O. Bair, and Irwin P. Levin, Ride Sharing: Phsychological Factors. Transportation Engineering Journal, November 1977.

3. Baldassare M. Ryan, Sherry Ryan, and Cheryl Katz. Suburban Attitudes Toward Policies Aimed at Reducing Solo Driving. Transportaion: 25 99-117. 1998.