Many of us have experienced the frustration of idling in long lines of traffic, inching forward at what seems like an interminable rate. Unfortunately, traffic congestion like this is a daily occurrence in many of the world’s fastest growing cities, such as Mexico City, Bangkok, Istanbul, and Rio de Janeiro.
Not only are congested roads an annoying inconvenience and a major waste of time, they also significantly contribute to poor regional air quality by raising concentrations of PM, CO, NOx, and ground-level ozone. In fact, a recent study finds that traffic contributes to 47.6% of Beijing’s declining air quality. That same study also concludes that air pollution worsens disproportionately as traffic congestion escalates.
So what can be done? Cities can adopt policies to expand mass public transit infrastructure, incentivize use of public transit, or revitalize urban planning to reduce suburban sprawl. Alternatively, a number of cities, including São Paulo, Mexico City, Santiago, Bogotá, and Beijing have turned to restricting the number of personal automobile on their roads. One policy proposal that some cities have adopted is to charge drivers for using certain roads during specified days and times. Revenues from these fees could then be used to invest in additional infrastructure, such as public transportation, that would eventually decrease the number of drivers on the road. However, convincing drivers to pay to use public roads is another matter.
A potentially more politically feasible policy is to restrict the number of vehicles allowed on the road during a given time period. In addition to the cities mentioned above, New Delhi and Jakarta have piloted or implemented such driving restriction policies. Typically, whether a driver is allowed on the road or not is determined by the last digit of their car’s license plate number, thereby randomizing the burden of the restrictions.
But many big question remains: Do these driving restrictions actually work? Will drivers follow the rules and keep off the roads during their restricted days? Will they circumvent the rules by buying a second (possibly more polluting) car? Will this have any effect on reducing air pollution? Will commute time increase for those seeking alternative transportation modes? And most importantly, will they be enough to solve the traffic and air pollution problems plaguing the cities? Research attempting to answer these questions is ongoing, but we highlight evaluations of driving restriction policies from two recent case studies: Beijing and New Delhi.
Beijing’s vehicle restriction policy was initially instituted for the 2008 Olympics and is the first of its kind in China. Restricting license plates ending in certain digits from driving on specified days has removed 20% of vehicles on weekdays. Total vehicle numbers are further restricted by limiting vehicle registration through a lottery system. Medium-run evidence points to improvements in traffic and no significant increase in commute times due to the policy adoption. Furthermore, traffic conditions appeared to improve during the study period as car purchasing quotas were implemented and violation sanctions strengthened.
There are notable differences between the lottery system that Bejing has implemented and a system that allocates licenses through auction. While a lottery system brings in no revenue stream for the city as an auction system would, there is significantly slower growth in the number of automobiles on the roads. Many families wait until they have the means to purchase a vehicle before they apply but another portion of the public applies for the lottery, then never purchases or registers a vehicle if selected. Because car owners are not determined by the highest willingness to pay, Bejing’s vehicle lottery is viewed as a fair and equitable policy with health and environmental benefits.
Using real time speed data from Uber India, researchers have found evidence indicating that a license plate restriction in Delhi has successfully improved air quality within the city. The preliminary results of the Odd-Even Program in Delhi, which restricts cars in odd ending license plates to drive only on odd days and even ending plates only on even days, contradict the findings of notable policy failures in Mexico City known for increasing pollution. Speed increases of 5.4% suggest less traffic and cars on the road, which further implies lower idling time and improved mileage. January 2016 data highlights particulate matter levels that increased in Delhi and the surrounding cities, but at a lesser rate than the rest of the region by 10-13%. This is a relative improvement, but one that might prove valuable for regional air quality.
The evidence from Beijing and Delhi is promising, but by no means a panacea. Developing countries are experimenting with a number of policy drivers that will impact their burgeoning metropolises. One potential avenue could be parallel policies to incentive use of mass public transit alongside vehicle restriction policies. As researchers tug on many different strings to improve health, pollution, and quality of life for the citizens of these cities through restrictive policies, establishing reliable and low emission mass transportation solutions will be an important avenue to overhaul the personal automobile revolution that developing countries continue to face.
By Samantha Childress and Lauren Masatsugu.
This entry was first posted in Duke Household Energy and Health Initiaitve Blog on February 13 by marc.jeuland@duke.edu.