Planning Professor Advocates a Higher Price for Driving

Michael Manville

Michael Manville, assistant professor in CRP. William Staffeld / AAP

January 12, 2015

If you want to reduce traffic congestion, air pollution, and global warming, pumping more money into public transit isn't the answer. Americans simply need to drive less, and the only way to achieve that is to make driving more expensive, says Michael Manville, assistant professor in the Department of City and Regional Planning.

Currently, Manville says, drivers do not pay the "full social costs" of driving because the price they pay does not account for the negative consequences it causes, from emitting pollutants to increasing the risk of accidents to clogging highways.

"The idea is not for people to give up their cars — that's not desirable," Manville says. "The question is, if you have a car, how much do you use it? In the aggregate, Americans drive more than they would if they had to pay its real price."

In the United States, Manville says driving has been subsidized by local, state, and federal governments — the average gas tax in the U.S. is less than 50 cents a gallon, compared to more than $3 a gallon in Germany — and most importantly through the free use of roads. Congestion occurs because roads are free, he adds, and like many underpriced goods, they are prone to shortages. To reduce clogged roadways, Manville says cities need to create electronically managed congestion tolls, which use changing toll fees to keep traffic moving at a set speed.

Cities could program tolls, for example, to maintain the lowest price that allows traffic to travel at 65 mph. "So at eight in the morning, when many people want to get on the road, the price might be higher," Manville says, "whereas at three in the morning, it might be close to zero."

San Diego County uses traffic congestion tolls on a highway that bases the system on an algorithm that changes the toll rate every six minutes, adjusting to demand. Singapore, which also uses electronic road pricing for its freeways, is another example other cities should look to, Manville says.

While some transportation planners advocate increased investments in public transit usage, Manville says a focus on building more transit distracts people from the fact that driving is "mispriced." A study he recently coauthored shows that while voters strongly favor increased funding for public transportation, that support rarely translates into less driving or more public transit use.

Published in the journal Transportation in September, the study finds that tax increases in 21 local ballot measures from 2001 to 2003 were approved, on average, by 63 percent of voters. Ten years later, however, the proportion of commuters who drove alone in these communities had dropped by only two points, from 87 to 85 percent — the same as the national average — while the share of transit riders remained at 5 percent.

"Support for public transportation is very strongly associated with people's concerns about broad social problems," Manville says. "People who are worried about the environment, worried about global warming, and worried about congestion also support spending money on transit. But there was no association at all between people supporting public transportation and their desires to drive less or actually use transit themselves."

For Manville, this illustrates the dangers of building transit to solve problems that mainly occur on roads: If people will not use transit, why build it in the first place? "If everyone thinks, 'I'm going to finance it and other people are going to ride it,' then what you have is a lot of people spending a lot of money and no one riding the train," he says. "And then you run the risk of having wasted a lot of money."

By Sherrie Negrea

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