New charts released by the State Smart Transportation Initiative, a sustainable transport program funded by the Department of Transportation, showing overall vehicle miles traveled (VMT) at its lowest level since 2003 and per capita VMT at its lowest level since 1998, lead Jaffe to ask if the United States has, in fact, reached "peak driving."
With the trend seemingly established, Jaffe investigates the possible causes, including gas prices and the embrace of sustainable land-use patterns. And, it's upon this latter explanation that he elaborates.
"A brief analysis by SSTI found a weak connection between VMT and gas prices, and a rather strong one between vehicle miles and urban density...With a rise in urban density comes an ease of accessibility. On its own that would lead to an increase in trip-making, but accessibility also makes the length of each trip shorter and more direct, and creates a favorable situation for the use of non-automobile travel modes."
According to Jaffe the connection between higher density and reduced VMT is supported by at least two other studies conducted by Australian researchers and the Brookings Institution.