Driving in the 21st century: Current trends, future needs

For over half a century, the transportation and urban planning fields have worked within a policy framework that assumes that demand for driving will always increase, both in the aggregate and at the individual level. However, the last decade has called that assumption into question. 

For the first time in national history, aggregate driving levels have been relatively flat for a prolonged period, and per-capita driving has actually declined. This turnaround, though a positive trend in terms of environmental impact, creates a challenge with regard to how the country plans, designs, builds, and finances transportation in our cities and metropolitan areas. Considering these inflated projections, are we chasing an outdated model?

vehicle miles traveled

Source: State Smart Transportation Initiative analysis of United States Department of Transportation data
NOTE: C&P and HPMS reference USDOT’s Conditions and Performance reports and Highway Performance Monitoring System, respectively.

In January 2015 the Brookings Institution, Frontier Group, and the U.S. PIRG Education Fund convened a group of experts from academia, non-profits, and government to discuss these dynamic changes in personal transportation trends and their implications for public policy. To facilitate an open dialogue, individual participants’ comments were not recorded. And as a result of the wide variety of perspectives incorporated, the meeting produced no consensus as to the causes of recent trends, failings in current policy frameworks, or singular public policy responses.

However, several common themes emerged from the dialogue that lay a foundation for future research, debate, and public policy action:

Better data—Current sources of transportation data were generally judged to be inadequate for understanding the causes and implications of recent changes in transportation behaviors, either in the aggregate or at the local or metropolitan level where critical transportation investment decisions are often made. Participants suggested several steps that might be taken to fill the data gap, including moving to a continuous National Household Travel Survey and aggregating data from cell phones, GPS, and other sources to provide richer, more up-to-date information on how Americans travel. Likewise, there was a shared interest in supporting open data protocols, both to promote transparency and foster new analytic findings from the civic sector. Such data improvements, in turn, could help incorporate the experiences of the last decade into transportation planning.

More flexible planning—The current “predict and provide” paradigm in transportation—in which transportation officials plan infrastructure investments based on projected needs 20 or 30 years into the future—was seen as imperiled amid stalled driving demand and growing interest in multimodal alternatives. Some planners and policymakers are adjusting to recent changes in driving trends by revising forecasts and reevaluating the appropriateness of proposed projects, both motorized and non-motorized. Others are embracing tools such as scenario analysis and vision-based planning that enable citizens and public officials to evaluate the implications of several alternative “futures” and prioritize investments that lead toward the most desirable outcomes. Yet, many agencies continue to rely on outmoded assumptions and tools for forecasting travel demand, and continue to communicate the results of those analyses to the public with more certainty than is warranted. New planning tools, and new ways of understanding and communicating uncertainty, are needed for this new era.

Revisiting priorities—While participants came to no consensus about how transportation investment priorities should change amid shifting travel trends, many expressed the need for more flexible, dynamic, and data-driven processes for prioritizing transportation investments, as well as the need for moving beyond outdated modal “silos” in allocating transportation funds. Some questioned whether increasing uncertainty about the future—for example, the accelerating pace of technological change—should lead to greater caution in proceeding with transportation “megaprojects” and a greater emphasis on small-scale solutions to transportation challenges. In general, however, participants agreed that changes in transportation trends should influence public policy and investment decisions, and that current transportation policy frameworks often fail to accommodate such changes.

Dialogue participants agreed to continue to share information regarding changing transportation trends, and the event organizers are currently considering ways to both expand and focus the discussion in order to ensure that America makes smart investments in transportation that fully take into account the nation’s evolving desires and needs. The country could be at a key inflection when it comes to how we build our cities and metro areas, making it imperative that we understand where we are and where we might be going.