Changing Travel Behavior: Punishment vs. Reward

Being in the business of finding ways to change travel behavior, I have dabbled in both reward and punishment. Charging for parking as a tool to get employees not to park in on-street spaces is a form of punishment, while giving out iPods to those who carpool a certain number of days each month is a reward. I have never thought that one might be more effective than the other until I read Eric Jaffe's piece, "Should We Pay People to Drive Off Peak," in Atlantic Cites Place Matters.

He writes about a group of researchers led by Taede Tillema of the University of Groningen, in the Netherlands, who recently designed a study to compare the effects of congestion pricing (punishment) to a Dutch program called "Spitsmijden," or "peak avoidance" (reward).

"In an upcoming issue of the journal Transport Policy, Tillema and colleagues report that a reward system like "Spitsmijden" may indeed be more effective than punishments."

The researchers combined data from a previous study and a previous survey and found that paying people not to drive during peak times changed behavior 37% of the time, whereas boosting tolls during peak times changes behavior only 15% of the time. A nagging question, as the author points out, is if paying people not to drive during peak times works best, who will pay them?