On Congestion Charging: Carrot or Stick?... Mixed Responses

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Stanford University

This morning's New York Times science section reported on a Stanford experiment on getting drivers to use the roads on its Palo Alto campus at off-peak times: allow them to enter a lottery to win $50 if they avoid rush hour.

Stanford reports huge success, and so do drivers, who say their commutes have been reduced by as much as 18 minutes, from 25 down to seven.

Here's how the story begins:

"Balaji Prabhakar, a professor of computer science at Stanford University, thinks he has a better way.

A few years ago, trapped in an unending traffic jam in Bangalore, India, he reflected that there was more than one way to get drivers to change their behavior. Congestion charges are sticks; why not try a carrot?"

So, we wondered, could a carrot reduce congestion in a big city, like New York, and not just on Palo Alto's bucolic, palm-lined campus?

Not much enthusiasm for that idea.  "How do you pay for it?" wondered Kathryn Wylde, president and CEO of the Partnership for New York City, in an email. Wylde  has been a big booster of congestion pricing to reduce traffic in midtown Manhattan. Also, she notes, there's "no net reduction in carbon footprint."

Paul Steely White, president of Transportation Alternatives and Wylde's partner in the failed attempt to bring congestion charging to New York, said he tended to agree with transportation expert Charles Komanoff, who was quoted in the article as saying:  “'The incentives will be far too small. You really do need big disincentives (big sticks). Little carrots won’t do the job of changing drivers’ decisions' in New York or in San Francisco."

But White said a pilot "would be great."

Rachel Weinberger, a University of Pennsylvania professor and expert in everything having to do with driving, says there's evidence on both sides. If a woman can reduce her commute by 18 minutes, Weinberger muses, no matter what happens in the lottery, she would have "won" back at least $50 in a month of that kind of time savings.

"It makes me wonder, if as a matter of public policy, we really need to be so concerned about the 'cost' of congestion.  In terms of paying people to 'behave the way we want them to'  it seems that every time I drive in earlier than the congestion charge takes effect I'm paying myself the charge. "

Weinberger describes a Seattle experiment where people were given an account and then drew down on it according to when they drove --  off-peak was cheaper than peak. In the experiment, they could keep what was left at the end. There was a 5-10 percent drop in driving.

"So there's some evidence that people behave irrationally and some that suggests they behave rationally after all."