El Gridlock?

October 30th, 2008

Traffic in Mexico City

For a little international perspective, last week I was traveling in Mexico City and got to experience firsthand the joys and challenges of navigating that city’s roadways. Having done some thinking about how cities can regulate their traffic problems in my home town of New York, I was interested to see the effects of “Hoy No Circula” a program implemented by the government in Mexico City in late 1989 to limit the number of cars on the road. The goal of the program was both to address traffic issues but also primarily an effort to improve the city’s air quality. Though there are a handful of exemptions, the basic idea of the program is that one day each week from Monday-Friday there is a prohibition on driving in the city depending on the last digit of each car’s license plate. For example, if the last digit of your license plate is 5 or 6, you are not allowed to drive on Mondays.

Though an interesting concept, and one that has been replicated in Sao Paolo, Bogota and Santiago, I must say that experientially it was hard for me to believe that there were 20% fewer cars on the road as I sat in bumper-to-bumper traffic on the way from the airport. And as it turns out, my experience may not have been all that far off from the truth. According to an article published in the February Journal of Political Economy by University of Michigan Asst. Professor of Economics Lucas W. Davis, air quality tests have shown no improvement in the city as a result of the driving restriction program. The study shows that there has been no demonstrated increase in ridership of the public transit system on either subways or buses. Additionally, evidence from vehicle registrations and automobile sales have shown that the program has actually lead to an increase in the total number of cars in circulation as residents buy additional cars so they may continue to drive everyday without concern of their license plate number. For more on the study, see http://www-personal.umich.edu/~lwdavis/df.pdf.

This article raises interesting questions about a local government’s ability to change drivers’ behaviors and preferences in selecting their methods of transportation. Would such a driving restriction program see the same effects if implemented here? Would drivers just find a way around the regulations to continue driving in much the same way? And could perhaps the fight against congestion pricing in New York last year be seen as the same type of rejection of a local government imposition of restrictions on the free movement of its citizen drivers? This study, and the seemingly unresolved fate of congestion pricing in New York, remind us of the uphill barrier that cities face in trying to get their citizens to move away from a life built around “el coche” (the car).