Travel Demands Are A-Changin', and That's Good News

Come gather 'round people wherever you roam
And admit that the waters around you have grown
And accept it that soon you'll be drenched to the bone
If your time to you is worth savin'
Then you better start swimmin' or you'll sink like a stone
For the times they are a-changin'

Come writers and critics who prophesize with your pen
And keep your eyes wide the chance won't come again
And don't speak too soon for the wheel's still in spin
And there's no tellin' who that it's namin'
For the loser now will be later to win
For the times they are a-changin'

Bob Dylan - The Times They Are A-changin'

I just finished reading The End of Traffic & the Future of Transport, by professors David (The Transportationist) Levinson and Kevin (Vehicle For A Small Planet) Krizek. This book is very affordable ($4.95) and quick to read. I recommend it to anybody interested in transport policy and planning.

Levinson and Krizek examine how current trends, including aging population, changing consumer preferences, new communications and vehicle technologies, and changes in transport and land use planning, will affect future travel demands, that is, how and how much people will want to travel. They conclude that in most of the developed world, private automobile travel has approximately peaked in total and declined per capita, and users increasingly want more diverse transport systems, with better walking, cycling, ridesharing (e.g., Uber and Lyft), carsharing, telework, and, possibly, autonomous vehicles. They are overall positive about these trends and critical of planning that fails to respond.

The writing is engaging; the authors use numerous stories, many personal, and others from popular culture, to illustrate their ideas. For example, they describe motorists' five stages of grief (denial, anger, bargaining, depression, and acceptance) when confronted by road space repurposing. The book is full of insightful illustrations and is thoroughly referenced.

Much of the information has been previously published, but it is useful to have it assembled and organized in a book with an integrated narrative. One interesting new issue they raise is their conclusion that roadway networks are overbuilt and should contract somewhat, with some rural paved roads becoming gravel, and some urban traffic lanes shifting to wider sidewalks, bike and bus lanes, and more greenspace. They argue that these changes are economically justified and politically expedient since voters are so reluctant to support transportation funding increases; in fact, they devote an entire appendix to "(Why) is Transport Underfunded?"

This book and the literature it cites is personally validating. In 2006 I wrote an article, “Changing Travel Demand: Implications for Transport Planning,” published in the ITE Journal, that made similar predictions, which at the time seemed speculative, so the article was criticized and almost rejected. We now have a decade of evidence of declining automobile travel demand and increasing demand for alternative modes.

I have three minor criticisms. First, David and Kevin are optimistic about new technologies—I tend to be more skeptical; I believe they overestimate electric and autonomous (self-driving) vehicle benefits. For example, they accept with little critique the claim that autonomous vehicles will significantly reduce traffic congestion and accidents. My analysis suggests that net benefits are likely to be smaller than they assume: safety benefits will be offset by new risks, such as "death by computer," and they may stimulate more peak-period vehicle travel, which increases traffic and parking congestion, accidents and pollution emissions. They state that, "Soon parents will be able to order a self-driving car to take their children to soccer practice," which I consider unlikely unless "soon" refers to future decades. Even after the technology is demonstrably safe, I doubt that many parents want their young children to travel alone in a self-driving car. Many of their predictions, such as autonomous vehicles operating at high speeds and densities on dedicated lanes, require dedicated lanes for these vehicles, and so are unlikely to occur for many decades, if at all. 

Second, they present these changes as given rather than contingent: yet many of the vehicle travel reductions they predict can only occur if public policies change to better support walking, cycling, public transit, telework and compact, multimodal development. I think they could be clearer that potential benefits depend on such reforms.

Third, although the book emphasizes the importance of shifting from "mobile-oriented" to "accessibility-oriented" transport planning, and the authors are leaders in the field, they give surprisingly little consideration to accessibility-improving land use strategies such as smart growth policies and transit-oriented development. Although they mention that vehicle parking imposes large economic costs, and they highlight the parking cost savings that could be provided by shared and autonomous vehicles, they fail to mention parking pricing reforms (unbundling, cashing out, and efficiently pricing parking) as important strategies for more efficient transport and community development.

Despite these minor criticisms, I like the book and consider it a useful tool for challenging excessively automobile-oriented transportation planning. It will make an excellent text for many planning courses. It offers a positive vision of a more diverse, efficient and equitable transportation future. Well done David and Kevin!

This book should be a wakeup call to planners who predict future travel demands by simply extrapolating past trends. They even include a version of the famous graph showing how official projections have greatly overstated future vehicle travel growth. For example, according to these projections, U.S. vehicles should now travel nearly four trillion vehicle-miles, a third more than the three billion VMT that actually occur. 

Not everybody has got the message that it is time to recalibrate travel projections. The Texas Transportation Institute’s latest Urban Mobility Scorecard estimates future vehicle traffic by simply extrapolating VMT growth rates between 2000 and 2005, which was before Baby Boomers began to retire and Millennials reached driving age, carsharing and bikesharing were new concepts, Internet shopping was uncommon, and Uber did not exist (it was founded in 2009). As a result, its predictions of huge increases in traffic congestion costs are suspect; in fact, traffic congestion costs will probably stay about the same if we continue with current planning practices, and will decline overall in cities that respond to changing travel demands, for example, by creating bus lane networks, improving walking and cycling conditions, and supporting more affordable-accessible housing development.   

These two documents reflect fundamentally different assumptions about travel demands and planning goals. The Scorecard assumes that demands are inflexible and urban travelers lack alternatives to driving, and portrays automobile commuters as victims of an unresponsive system rather than masters of their own fate. This contrasts with Levinson and Krizek’s optimistic vision of changing travel demands, improved travel options, and responsive transport system users.

The Scorecard’s analysis methods have been criticized by experts for omissions and biases:

The Top Ten Reasons to Ignore TTI’s Urban Mobility Report

News Flash: Congestion Still Not Getting (Much) Worse

Hey Look, That Flawed Texas A&M Traffic Study Is Back And Grabbing The Usual Headlines

TTI Congestion Scores Prove Road Expansion Isn’t the Answer

Pro-Transit Group Attacks D.C. Traffic Congestion Report As Deeply Flawed

Meet the Most Traffic-Jammed Cities in America

Rethinking Urban Traffic Congestion To Put People First

Annual Congestion Report is Flawed, Biased, and Ignores Smart Growth Solutions

New Traffic Congestion Report Raises More Questions Than It Answers

2015 Urban Mobility Scorecard: Still Measuring Urban Travel Conditions Incorrectly

How Not To Measure Traffic Congestion—Hold the Hyperbole, Please!

Contradictory Conclusions and Disappearing Data. (This column describes a significant discrepancy between the Scorecard's estimates and those reported by Inrix, which provides the source data. Although the Scorecard estimates that congestion increased 4.7% between 2010 to 2014, Inrix reported a 29% decline. Inrix subsequently removed the data, but not before it was captured.)

The Scorecard is classic scaremongering. Its recommendation for an "all hands on deck" response is the antithesis of good planning, which requires comprehensive evaluation and prioritization of potential solutions. This is important because some congestion reduction strategies provide significant co-benefits, such as consumer savings, traffic safety and parking cost savings, while others, by inducing additional vehicle travel and sprawl, contradict other planning objectives. 

The Urban Mobility Report authors overplayed their hand; by producing propaganda rather than objective analysis they lost many supporters, particularly government agencies which expect academic quality research. The current edition notes that this is likely to be the last available free to the public. I am sorry to see this outcome; credible congestion costs data is very useful for planning and research purposes. Had TTI responded to earlier criticisms, they could have maintained support for this project.  

For More Information

APTA (2013), Millennials and Mobility: Understanding the Millennial Mindset, American Public Transit Association.

Tony Dutzik and Phineas Baxandall (2013), A New Direction: Our Changing Relationship with Driving and the Implications for America’s Future, U.S., Frontier Group.

Economist (2012), “Seeing the Back of the Car,” The Economist, 22 September 2012.

ITF (2013), Long-Run Trends in Car Use, Roundtable 152 Report, International Transport Forum.

Susan Handy (2015), How Travel Demand Has Been Changing, Asilomar Conference.  

Todd Litman (2006), “Changing Travel Demand: Implications for Transport Planning,” ITE Journal, Vol. 76, No. 9, September, pp. 27-33.

Todd Litman (2014), Smart Congestion Relief: Comprehensive Analysis Of Traffic Congestion Costs and Congestion Reduction Benefits, Victoria Transport Policy Institute, presented at the Transportation Research Board Annual Meeting.

Chris McCahill and Chris Spahr (2013), VMT Inflection Point: Factors Affecting 21st Century Travel, State Smart Transportation Initiative.

NCHRP (2014),Strategic Issues Facing Transportation: Volume 6: The Effects of Socio-Demographics on Future Travel Demand, Report 750, National Cooperative Highway Research Program, Transportation Research Board. 

Julia Pyper (2012), “Has the U.S. Reached “Peak Car”?: Traffic Is Easing As More Americans Are Deciding To Drive Less, Sell Their Cars Or Not Buy One At All,” Scientific American, 25 July.

Michael Sivak (2013-2015), Has Motorization in the U.S. Peaked?, University of Michigan, Transportation Research Institute. This is a series of reports which examine various factors that are contributing to peaking motor vehicle travel.

Clark Williams-Derry (2010-2013), Dude, Where Are My Cars? Sightline Institute.