What will it take for people to choose sustainable modes of transportation?

ASU Professor Ram Pendyala teams up with University of Texas at Austin researchers to find out why it's so hard to get people to use mass transit options


June 1, 2022

In the recently enacted Bipartisan Infrastructure Law, more than $550 billion has been earmarked for transportation infrastructure projects across the United States. That includes a large portion for the improvement and development of transportation modes that are more sustainable — such as mass transit.

Currently, travelers spend multiple hours per week in their personal vehicles driving to and from work, school or other locations. The goal of the planned investments in new transportation modes is to reduce the number of personal vehicles on the road to alleviate their environmental impact. Aerial photo of highway interchange. Hundreds of billions of dollars are set to be spent building up existing infrastructure across the United States, including mass transit systems, in hopes of providing more sustainable transportation options. Photo by Aleksejs Bergmanis/Pexels Download Full Image

Ram Pendyala, professor and director of the School of Sustainable Engineering and the Built Environment, one of the seven Ira A. Fulton Schools of Engineering at Arizona State University, teamed up with Professor Chandra Bhat and his research group at the University of Texas at Austin to investigate why people travel the way they do and what it would take to get them to choose public transportation and other alternative modes instead of driving themselves.

The results of their investigation are documented in “Influence of Mode Use on Level of Satisfaction with Daily Travel Routine: A Focus on Automobile Driving in the United States,” a refereed article that has just been published in Transportation Research Record: The Journal of the Transportation Research Board by SAGE Publishing.

Pendyala and Bhat answered some questions about the insightful results they obtained. Here are their combined responses.

Question: Why is it important to study people’s use of different modes of transportation?

Answer: The country is attempting to reduce greenhouse gas emissions, render communities more sustainable and livable, and combat the ill effects of climate change. The latest Bipartisan Infrastructure Law has hundreds of billions of dollars of investments aimed at enhancing transit systems, as well as bicycle and pedestrian transportation networks, implementing strategies to better manage and reduce automobile traffic, and motivating the traveling public to eschew the use of automobiles for daily travel. Policymakers and the public alike are counting on these investments and strategies to deliver a more sustainable mobility future.

Q: What challenges are planners and policymakers facing when trying to convince travelers to switch to sustainable transportation options?

A: Historical evidence suggests that it has been notoriously difficult to realize any substantial decrease in vehicle use despite decades of attempts at doing so through a variety of investments, programs, educational campaigns and travel demand management strategies. With the nation preparing to invest large amounts of money to expand sustainable transportation modes in the hope that this will naturally draw travelers out of their cars, it is absolutely imperative to understand that such investments and strategies alone are unlikely to yield results anywhere close to what policymakers and the public seek to achieve.

Q: What are the main motivators behind people continuing to travel as they have?

A: The common perception is that Americans dislike driving and experience a lower quality of life when they are dependent on their automobile for daily travel. It is often thought that providing alternative modes of transportation with a high level of service may promote a shift to more sustainable modes of transportation. However, that can happen only if the original premise that automobile use and dependency contribute to a lower quality of life is true.

So, we conducted a survey in the four auto-centric metropolitan regions of Phoenix, Arizona; Austin, Texas; Atlanta, Georgia; and Tampa, Florida, to understand how Americans travel and how satisfied they are with their daily travel routine. The data collected showed that people are largely satisfied with their daily travel routine despite living in metropolitan areas with very limited transit service. The results did not support the premise that automobile use is associated with a lower quality of life. In fact, it showed that those with higher levels of relative amounts of driving are more satisfied with their daily travel routine. This explains why decades of efforts aimed at swaying drivers into more sustainable modes of transportation have proven futile in most contexts in the United States and around the world.

Q: What changes can be made to bring about a shift toward sustainable transportation modes?

A: Based on our study and evidence to date, it is clear that two conditions have to be met for significant shifts in mode use to occur. First, transportation alternatives need to be super competitive and comparable to the automobile in terms of level of service. This is extremely difficult to achieve in the absence of prohibitively massive investments of resources in transportation alternatives. Second, the use of automobiles needs to be made burdensome through restrictive and punitive measures, such as tolls and fees, parking restrictions and limiting roadway capacity. Satisfying these conditions is invariably difficult, both from a financial and a public acceptance standpoint.

Hence, we feel greater progress in reducing vehicle use can be achieved through coordinated land use — transport planning and zoning policies that promote high-density, mixed-use developments characterized by walkable, transit- and bicycle-friendly environments. This will allow people to reach a large variety of destinations without having to travel by car. Also, the carbon footprint of personal automobile travel can and should be reduced through an aggressive campaign to accelerate transportation electrification, enabled by incentives and the widespread deployment of electric vehicle charging infrastructure.

In addition to Ram Pendyala at ASU and Chandra Bhat at UT Austin, significant work and contributions were made to the study by co-authors Tassio Magassy and Irfan Batur, doctoral students and graduate research associates at ASU; Aupal Mondal and Katherine Asmussen, doctoral students and graduate research associates at UT Austin; and Sara Khoeini, assistant research professor at ASU at the time of the study. The study was partially funded by the U.S. Department of Transportation through its University Transportation Centers Program.

Monica Williams

Communications Specialist, Ira A. Fulton Schools of Engineering

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