Jonas Eliasson, a co-designer of Stockholm's famous congestion pricing system, recently gave a TEDx talk called "How to Solve Traffic Jams" (via The Transportationist). It's one of the clearest and most persuasive discussions of road pricing I've ever heard, and with the video nearing 300,000 viewers, I doubt I'm alone. I've summarized the talk here, but if you've got ten minutes to spare I highly recommend the whole thing.
Too often traffic planners try to determine what people should do instead of driving during rush hour, says Eliasson. He would prefer that cities provide the right incentives and let people take it from there. "You don't plan the details—people will figure out what to do, how to adapt to this new framework," he says.
So what are the right incentives? The answer, in the case of Stockholm, turned out to be just a couple euros per driver. That small fee removed 20 percent of rush-hour cars, says Eliasson, which may not sound like a ton but makes a very noticeable difference. The image behind Eliasson to the left is Stockholm on January 2, 2006, the day before the charges took place; the image to the right is January 3:
What's so fascinating about Stockholm's road pricing is how consistent the city's traffic reductions have been over the course of the program. The one exception was during a period between August 1, 2006, when the original trial ended, and August 2007, when a successful referendum brought pricing back. Traffic during that period neared its pre-pricing levels, and the increase in congestion was immediate. Here's another before and after view from 2006:
"You even have to admire the car drivers," says Eliasson. "They adapt so extremely quickly."
Not just quickly — completely. As Eliasson explains, people were "fiercely" against the pricing program at first, with roughly 70 percent opposing it. By the middle of 2011, however, the polls had flipped and 70 percent supported the program. As Eliasson puts it, 70 percent of people in Stockholm now wanted to pay for something that used to be free.
Things got even more interesting when experts tried to figure out which drivers had changed their minds. That turned out to be a tough question to answer, because half the drivers now thought they'd always liked congestion pricing as much as they did now. In other words, people adapted their behavior so thoroughly that they couldn't even recall what it used to be.
Eliasson sees the whole experience as proof that behavioral nudges work:
This is the power of nudges when trying to solve complex social problems. When you do that, you shouldn't try to tell people how to adapt. You should just nudge them in the right direction.
Congestion pricing programs aren't perfect, and the rates must be monitored closely to sustain the effect. (Nor are they the only types of mode-switching incentives that cities can offer.) If implemented wisely, however, they may be the best hope cities have for solving a traffic problem that often seems hopeless.