Report: Lower VMT trend is here to stay

By Eric Sundquist

FHWA today released its monthly travel-volume trend summary, showing that for the first quarter of 2013, aggregate national VMT was down 0.8 percent and per-capita VMT was down 1.5 percent compared to the same quarter of 2012. Rolling 12-month figures were also down in both categories.

The summary is just the latest evidence that Americans are driving less on average than they were a decade ago, and that even with population increases, total VMT is flat to slightly declining. But, given the long historic trend of consistently increasing vehicle miles traveled through the early 2000s, the question remains: Are we in a period of aberration that will eventually end, or has something really changed?

A new report by the U.S. PIRG Education Fund and the Frontier Group argues that the change is a durable one. Its findings generated considerable media coverage last week, from straight news accounts to at least one hilarious, profanity-infused one as well.

These stories highlighted the chapter in the report focusing on lower driving by the Millennial Generation. However, this aspect of VMT change already has been covered by a number of authors, including PIRG and Frontier, so the new report’s real interest may be in the way it brings together demographics and other drivers of transportation demand. When these are viewed together, the report finds, we see that many of the factors that created a strong upward push on VMT during the “driving boom” era now have moderated or are at least uncertain. In Table 1 below, green indicates conditions leading to higher VMT, red indicates conditions leading to lower VMT, and yellow indicates relative stability or uncertainty.

trends graphic

Table 1. Factors that influence driving. (U.S. PIRG Education Fund and Frontier Group, 2013.)

A more complete table might also include growing acceptance of compact and/or mixed-use land development, as well as maxed-out travel time budgets.

To estimate the level of aggregate national VMT going forward, the report examines recent changes in driving rate by age group. It describes three scenarios, ranging from a reversion to previous peak levels of per capita VMT to continued declines. The scenarios are shown in Figure 1.

Figure 1. Three VMT scenarios. (U.S. PIRG Education Fund and Frontier Group, 2013.)

Figure 1. Three VMT scenarios. (U.S. PIRG Education Fund and Frontier Group, 2013.)

All three scenarios indicate VMT that is lower than the historical trend, with wide-ranging implications for fuel tax revenues to congestion levels, suggesting a need for revised policy approaches.

Eric Sundquist is Managing Director of SSTI.