Millions of households in the United States lack safe and reliable transportation to get where they need to go. But while transportation insecurity is a very common form of material hardship experienced by US adults, only recently have researchers had a validated instrument to measure it.

A new study out in Social Indicators Research uses recent data and a newly validated measure of transportation insecurity to see how inadequate access to transportation compares and relates to other forms of material hardship in the United States. Impacting nearly 1 in 5 US adults, transportation insecurity makes it difficult for people to reach destinations critical to their well-being, including work, doctor’s offices, social services, grocery stores, and the homes of friends and family.

For the last few decades, researchers have investigated specific challenges that Americans experience in their daily lives with a set of survey questions created to expand our understanding of poverty. This scholarship has centered on a set of common survey questions that detect specific forms of deprivation. They ask individuals and households if they’ve experienced food insecurity, housing insecurity, utility shutoffs, inability to pay bills, or the need to forego medical care. But transportation issues have been left out of that story because, until recently, there was no validated measure of transportation hardship.

The Transportation Security Index

Over the past decade, Alexandra Murphy and University of Michigan alum Alix Gould-Werth have translated what began as observations in their respective qualitative research projects into the lives of people with low incomes into an important new metric for measuring inequity. The “Transportation Insecurity Index” is a validated measure that captures individuals’ experiences of transportation insecurity, or the condition in which, for lack of resources, they are unable to regularly get from place to place in a safe or timely manner.

In 2014, Murphy received seed funding from the Population Studies Center at the University of Michigan Institute for Social Research (ISR) to pursue the idea of developing a metric to understand and quantify the experience of transportation insecurity. The team worked to develop a definition of the concept of “transportation insecurity” and pulled together resources across ISR to develop the methods to measure it, with key contributions from methodologist Jamie Griffin, then working on the Panel Study for Income Dynamics, cognitive interviewing expert Lisa Holland at the Survey Research Center, and ongoing feedback from Brady T. West and the Survey Design Group. The work culminated with a validated index that has already been adopted to existing demographic surveys, including the “Omnibus Survey” of the Minnesota DOT. A future wave of the Health and Retirement Study, among the most important sources for understanding older adults in the United States, will include a module with the Transportation Security Index.

In a recent consensus report issuing recommendations to Congress and the US Department of Transportation (DOT), the National Academies of Sciences, Engineering, and Medicine (NASEM) recommended the widespread testing and use of tools to measure transportation insecurity.

“We modeled [the index] on the Food Security Index created in the 1990s and adopted by the Department of Agriculture,” said Murphy. “One of the things we thought was brilliant about the Food Security Index is that rather than trying to understand people’s caloric intake, or whether they’re eating the five categories of the food pyramid, they ask about the symptoms of food insecurity, as people experience it qualitatively in their everyday lives. They ask things like whether you had to skip a meal in the past month because you couldn’t afford food. Given the variety of ways people get around and the places they have to go, we sought to measure transportation insecurity similarly by asking people about their symptoms as experienced in their daily lives.”

The National Academies report notes this is a crucial shift because it expands the usual focus beyond physical infrastructure to understand whether transportation is meeting people’s needs.

The Most Prevalent Form of Hardship

Building on recent work investigating transportation insecurity and on material hardship, Murphy collaborated with Natasha Pilkauskas of the University of Michigan Ford School – also an affiliate of the Population Studies Center– to understand how transportation insecurity fits in with the more commonly studied forms of hardship. Understanding how different forms of hardship are interrelated can help policymakers craft policies that more effectively alleviate challenges that affect millions of Americans.

With a nationally representative survey of American adults, the researchers found that in 2022, 19% of Americans had experienced transportation insecurity in the past month. This figure surpassed all other categories of hardship: 16% reported food insecurity; 13% had unmet medical needs; 9% reported housing insecurity; 7% reported bill hardships, and 4% reported utility shutoffs.

The demographic groups most likely to experience transportation insecurity, including adults with lower incomes, those with a limiting condition, or who live in urban areas, are also the ones disproportionately affected by other hardships, especially food insecurity, the researchers found. 

The analysis revealed striking similarities between food and transportation insecurity. These two highly prevalent forms of hardship were also the most likely to go hand in hand, and to emerge from similar processes. The relationship between poverty and both transportation and food insecurity was also stronger than that of other hardships– although the relationship between income and transportation insecurity is less clear, the researchers said.

Transportation and Health

The researchers also investigated the association between transportation insecurity and physical and mental health. 

They found that people experiencing transportation insecurity are 6% more likely to self-report poor health, and 11% more likely to report depressive symptoms. The association between transportation insecurity and health is similar in magnitude to that of food insecurity and unmet medical needs.

“This was the first study to consider the extent to which transportation insecurity is related to other forms of material hardships,” said Pilkauskas. “There is a lot that remains to be learned, but with this study we know that transportation insecurity behaves similarly to other hardships, especially food insecurity. And this work underscores the importance of addressing transportation insecurity in efforts to reduce material hardship and improve health and well-being. Lots of policy attention goes to food insecurity – and rightly so –  but our study suggests that policymakers interested in improving material wellbeing and even health should also consider ways to address transportation insecurity.”

Alexandra Murphy is an assistant research scientist at Poverty Solutions, a faculty affiliate of the Population Studies Center at ISR, and the Associate Director of Social Science Research at Mcity. Her work examines how poverty and inequality are experienced, structured, and reproduced.

Natasha Pilkauskas is an associate professor of public policy at the University of Michigan’s Gerald R. Ford School of Public Policy and a research associate professor in the Population Studies Center at ISR. Her research considers how demographic, social safety net, and economic shifts in the U.S. affect families and children with low-incomes.

Contact: Tevah Platt