New Urbanists have advocated walkable cities and shorter commutes for years. But does investing in this approach -- what behavioral economists call "smart growth" -- simply look good on paper, or does it produce tangible results?
It does, according to a new study published in the B.E. Journal of Economic Analysis and Policy.
The study, conducted by Sudip Chattopadhyay and Emily Taylor of San Francisco State University, looked at the ways travel demand were impacted by the degree of "smart growth" in a given city. Their findings indicate that people are not as dependent on their cars as common wisdom might suggest. Instead, urban car use patterns are rather elastic. Just a 10 percent increase in "smart growth" amenities can reduce the number of annual vehicle miles traveled by 20 percent.
"We found that changing the way cities are designed would significantly reduce travel demand," Sudip Chattopadhyay, professor and chair of economics at San Francisco State, said Sept. 13. "People's travel habits would change, and they would drive less."
The study provides important insight for urban areas interested in reducing their carbon emissions.
Until now, automobile efficiency standards and carbon taxes have dominated the debate around carbon emissions in the United States. In August, the Environmental Protection Agency announced a new mandate requiring all automobiles to travel 54.4 miles per gallon by 2025. On a parallel front, John Voelcker of the Christian Science Monitor suggested last week that fuel prices should be brought in line with other Western nations:
"Until now, one of the most common means of reducing carbon emissions is implementing a fuel tax hike. "If gasoline prices in the U.S. were in line with those in almost every other industrialized country--closer to $8 a gallon than $4--consumers would be incentivized to cut their consumption, both by buying different cars and by driving less."
Chattopadhyay and Taylor's study indicates that smart growth might provide a third, and perhaps more effective, means of cutting carbon emissions. According to the study, a 10 percent increase in the cost of driving one mile only reduces annual miles driven by 18 percent: two percent less than implementing "smart growth" techniques.
As it turns out, then, walkability isn't just a best practice on paper. It does well in the real world as well.