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In New RAND Study, Visions of a Post-Driving Boom Future

A few months ago, in a report called A New Direction, we made the bold claim that the “Driving Boom” (defined as the period of steady increases in per-capita driving in the United States that began after World War II) is over. We posited a few scenarios for future growth in driving and demonstrated that even under the most aggressive conceivable scenario, driving would increase far less rapidly than is assumed by current government forecasts.

The implication: policy-makers are currently anticipating the need for far more new highway capacity than is likely to be truly necessary, creating the need for an urgent rethink of transportation investment priorities at the federal, state and local levels.

In late October, the RAND Corporation and the Institute for Mobility Research (an affiliate of BMW) released a new analysis, The Future of Mobility, with scenarios for future travel trends in the United States through 2030. The RAND analysis reinforces the idea that a return to steady increases in per-capita driving is unlikely under pretty much any conceivable circumstance – and that continued, long-term stagnation in driving is a possibility meriting serious consideration.

The RAND researchers evaluated two scenarios. The “Fueled and Freewheeling” scenario is one of cheap gasoline, expanding suburban sprawl, a rapidly growing economy and steadily rising congestion. The “No Free Lunch” scenario posits higher gasoline prices, a more aggressive regulatory stance toward global warming, innovation in vehicle and fuel technologies, rising urbanization, and increased telecommuting.

In short, “Fueled and Freewheeling” is a return to the trends of the 1980s minus the Cosby sweaters. “No Free Lunch” is an extension of the trends of the recent past. The researchers state that these scenarios “are indicative of a range of ‘plausibilities.’” In other words, while we have no way of knowing which of the scenarios is more likely to occur, we can feel pretty confident that the future is likely to lie somewhere between them.  

It is no surprise that the “No Free Lunch” scenario results in continued sharp declines in per-capita driving, with the total number of passenger miles traveled on highways increasing by a scant 2 percent between 2010 and 2030. Under that scenario, highway travel would never regain its 2007 peak before the end of the study period in 2030, despite continued population growth.

The more fascinating scenario, however, is the “Fueled and Freewheeling” scenario. One would expect that that this driving-friendly future world would be one of steady growth in vehicle travel. Not so: the RAND researchers found that per-capita passenger travel by vehicle under that scenario would still decline, albeit by a modest 0.1 percent per year. Total vehicle travel would rise as a result of population growth, but only by 15.5 percent by 2030, for an average annual growth rate of 0.7 percent – well below the average annual growth rates of the Driving Boom years and recent government forecasts.

Here’s what’s remarkable: the “Fueled and Freewheeling” scenario is supposed to be the upper bound of the range of “plausibilities.” The implication I take from all this is that if you are a transportation planner or policy-maker in the United States, and you are assuming a level of vehicle travel growth greater than 0.7 percent per year, you should have some serious explaining to do about why your projections are reasonable. And if you are a planner or advocate arguing that the recent stagnation in vehicle travel is likely to continue over the long term, you deserve a respectful hearing.

Of course, the transportation research and policy world is taking a long time to come around to this new reality. Federal agencies (see, for example, the Department of Energy) continue to forecast that vehicle travel will increase roughly twice as quickly as the level of growth seen as the upper bound of plausibility by the RAND researchers. And the situation is even worse in many states and at the local level, where scare-mongering forecasts of crushing future congestion – based on the assumption of continued increases in vehicle travel – are still used to justify massively expensive highway expansion projects.

The new RAND study is a great resource that I hope will help move us toward the conversation about a post-Driving Boom transportation policy for the United States – a conversation that, given the upcoming reauthorization of the federal transportation law, can’t happen soon enough.