Do driving restrictions work?

How can cities cut down on smog? One appealing solution is to restrict the number of cars allowed on the road. For instance, Beijing forbids cars with certain license plate numbers from entering part of the city on specific days of the week. But a new study suggests that this approach simply doesn’t work that well: About half of car owners flouted the rules and drove anyway.

Buenos Aires, Mexico City, Sao Paulo, and various cities in China have all tried out driving restrictions. Proponents argue that these policies are more fair than charging people to use roads. But researchers have found that the restrictions can backfire. For example, rich residents of Mexico City got around the rules by buying a second car — often an older car that spewed more pollutants — that they could use when driving the first car was off-limits. People in Beijing have even covered up their plates to avoid being caught.

The authors of the new study wanted to find out how effective the Beijing driving restrictions were. They analyzed data from a household travel survey on 5,392 trips taken by car, bike, bus, subway, or walking. Among those trips, they found 730 cars that should have been restricted according to the new driving rules.

Forty-eight percent of the car owners ignored the rules and drove on their “forbidden” days, the team reports in Transportation Research Part A. These drivers were more likely to take illegal trips during rush hour and in outlying areas with fewer surveillance cameras, patrols, and public transit options. Even though driving restrictions “have been regarded as a silver bullet to mitigate congestion problems… rule-breaking behavior is constant and pervasive,” the researchers write.

So if driving restrictions don’t work, what will? The team suggests that the government needs to adopt a combination of strategies, such as fuel taxes, tolls, higher parking fees, and better public transportation. Roberta Kwok | 28 August 2014

Source: Wang, L., J. Xu, and P. Qin. 2014. Will a driving restriction policy reduce car trips? The case study of Beijing, China. Transportation Research Part A doi: 10.1016/j.tra.2014.07.014.

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