Since 2004, driving as measured by the number of vehicle miles traveled declined, reaching a two-decade low in 2012. Slumping figures for VMT per capita, number of vehicles on the road, and the average age of drivers all seemed to be telling us the same story: We’d passed “peak car” in the United States.
But then things got complicated. As the economy grew and cheap gas got cheaper, VMT per capita started rising anew—it’s gone up for five years straight. So, is there a real long-term decline? And if so, what is—or was—driving it?
Among urbanists, the argument tended to favor the shifting preferences for younger people away from driving and toward more dense living that’s closer to work, plus the availability of more and better alternatives such as transit or biking. Others saw the driving decline as a short-term effect of the economic downturn, fueled by a combination of stagnant incomes and wages and of the widening gap between rich and poor.
Well, buckle up, because the biggest experts in the field are fighting it out in the Journal of the American Planning Association. Just what’s going on behind America’s driving decline is the topic of a recent special issue, published in January. With contributions from some of the leading students of the subject, it suggests there are no easy answers and still considerable controversy around these issues.
A meta-analysis of the issues by Mark Stevens of University of British Columbia suggests that changes in the way we live—a shift from more sprawling to more compact development—explains at best just a small share of the driving decline.
To get at this, Stevens conducts a meta-analysis of 46 different studies from 1996 to the present in light of the “5Ds”—density, diversity, design, destination accessibility, and distance to transit—originally developed by Reid Ewing and Robert Cevero.