By Chris McCahill
Estimates released by FHWA on Friday suggest that per capita vehicle miles of travel dropped again in 2013, making it the ninth consecutive year of decline (Figure 1). Total VMT in the United States increased by 0.6 percent from 2012, hovering just below 3 trillion, and per capita VMT dropped to 9,402 (the prior year’s initial estimate was revised to 9,412).
Unlike other past dips in driving, this recent downward shift has had no clear, lasting connection to economic trends or gas prices. Evidence suggests that the decline is likely due to changing demographics, saturated highways, and a rising preference for compact, mixed-use neighborhoods, which reduce the need for driving. Some key factors that pushed VMT upward for decades – including a growing workforce and rising automobile ownership – have also slowed considerably. SSTI released a report last September outlining the many contributing factors, with references to supporting literature.
By now, some DOTs have acknowledged the downward trends in their states and begun to question what it means for their agencies—particularly when it translates into falling revenues, as in Oregon. It appears this has not affected investment priorities significantly in most states, but it has changed the way some DOTs now view future travel needs. Several recently updated long-range transportation plans reflect this shift.
Maryland is an example of this trend. In 2009, the state’s long-range plan projected statewide VMT growth of 2 percent per year through 2030 (Figure 2). The plan dismissed the recent decline as a temporary consequence of high fuel prices and the economic downturn, asserting, “there is no clear evidence that Marylanders will continue to drive less in the future.” However, in its updated plan released just last month, the agency has left out projections entirely, declaring that “a return to strong annual VMT growth is unlikely and per capita VMT [...] is actually decreasing.” A handful of other states have either dampened their projections or shifted their focus toward VMT reduction goals and transportation demand management efforts.
These are important first steps for state DOTs, but it’s not yet clear how they will affect day-to-day business or project outcomes. Few DOTs maintain statewide travel demand models, so they often depend on regional planning agencies for local traffic projections on individual projects. Until these models are properly re-calibrated, they will still show large future traffic increases, due mainly to inflated trip rates and anticipated population growth in undeveloped areas. Major investments based on these projections will become riskier as travel demands change and revenues decline. However, once transportation agencies adjust accordingly, the slowing demand for new roads should free up resources for maintaining existing infrastructure, improving travel options, and optimizing system performance in already developed areas.
Chris McCahill is a Senior Associate at SSTI.