Researcher discusses transportation insecurity in Detroit and beyond

More than a third of Detroit residents (36%) can’t get from place to place in a safe or timely manner.

This is the main finding of a new study led by Alexandra Murphy, associate director of social science research at Mcity and assistant research scientist at U-M’s Poverty Solutions, and first author Lydia Wileden, a U-M alum and assistant research professor at the University of Connecticut.

They measured this with a tool created by Murphy and her team called the Transportation Security Index. One aim of the TSI is to help local governments plan transportation investments, similar to the way food security indices clarify what kinds of food resources are needed and where.

A report issued earlier this month by the National Academies of Science, Engineering and Medicine recommended the use of transportation security indices to guide local investments in transportation resources, naming the U-M index as a good example. Detroit’s transportation insecurity is more than twice the national average of 17% (established in 2022).

Here, Murphy discusses what the TSI can reveal about issues facing Detroit and other U.S. cities.

Why focus on transportation insecurity?

The ability to get to the places we need and want to go has a huge impact on an individual’s quality of life: It allows us to get to work, visit the doctor, attend parent-teacher conferences, search for housing, take care of our aging parents, visit friends, vote, and so on. Being able to do all of these things likely has implications for everything from our physical and mental health to our financial security and the flourishing of our children. Even if we’re not personally transportation insecure, the security of others can affect us: for instance, employers have a vested interest in their employees arriving to work on time.

The TSI allows us to identify who is (and is not) regularly able to get from place to place in a safe or timely manner, quantify how big of a problem transportation insecurity is, and assess—through measurement and additional data collection—how this impacts outcomes relevant to individual and community well-being.

Our results show that those demographic groups most vulnerable to experiencing transportation insecurity are groups that have the least access to opportunity, including people living below the poverty line and those with disabilities. The TSI allows researchers to investigate how inequality both drives people’s experience with transportation insecurity and is a result of it.

Why a transportation security index? How would it change the way transportation investments are made?

The TSI allows us to consider transportation at the individual level. For a long time, when we talked about making investments in transportation, we focused on two things: infrastructure and communities. We’ve long thought about improving people’s ability to get around by investing in roads, bridges, sidewalks, public transportation, and so on. And when we make those investments, we think about doing them at the neighborhood or community level.

Looking at transportation insecurity at the individual level allows us to see that investments in communities don’t always reach individuals within those communities. With the TSI, we can then begin to answer questions like: What shapes people’s transportation insecurity? Are they unable to pay for their car to be repaired? Is public transit too far away to access? The different challenges that people experiencing transportation insecurity face may require different policy responses.

Detroit represents the first time you’ve applied the TSI to a specific city. What stood out to you about the results that came back from the survey?

Many of the 1 in 3 Detroiters who experience transportation insecurity have had to reschedule appointments or skip trips altogether. Our data also reveal the more relational and emotional dimensions of transportation insecurity. Of Detroiters reporting any level of transportation insecurity, 84% reported feeling bad about their situation and 56% reported that their transportation issues impacted their relationships in the previous 30 days.

What do your findings tell us about the relationship between modes of transportation and transportation insecurity in Detroit?

Given Detroit’s sprawling, low-density built environment, it’s not surprising that Detroiters without cars are nearly three times as likely to experience transportation insecurity compared to car owners. We also see that owning a car in the motor city doesn’t fully solve insecurity. Many Detroiters have unreliable vehicles, share cars with other household members, or lack car insurance, which is very expensive in Michigan. All of this increases the likelihood of experiencing insecurity.

Regarding public transit, the vast majority of Detroiters, 82%, reported they had not used it in the past 30 days, and our results suggest the cost of transit cannot fully explain this low usage. There is research suggesting the closer one lives to transit, the more likely one will use it, but we’re not seeing that in Detroit. The average transportation-insecure Detroiter lives within a three-minute walk of at least one bus stop. Moreover, we find that as one’s distance from a transit stop increases, the likelihood of experiencing transportation insecurity goes down.

Perhaps it is because the routes people live close to don’t take them where they want or need to go. Perhaps it is because the routes available involve commutes that are too long. But having identified this relationship suggests we need more research to understand what it will take to make our transit systems better serve those who are transportation insecure.

How is the TSI being used beyond Detroit?

One example is the Mobility, Access and Transportation Insecurity demonstration program at the University of Minnesota. It is using the TSI to evaluate whether different kinds of investments in transportation are moving people from “transportation insecurity” to “transportation security.”

The state of Minnesota and some counties are including the TSI in surveys, documenting the prevalence of transportation insecurity. By including it in future surveys, these governments will be able to see if transportation insecurity is going up or down, which will help them understand whether their investments are moving the needle.

Academic institutions have also been partnering with local communities to understand what transportation insecurity looks like in their own backyards. For instance, in addition to Detroit, the Detroit Metro Area Communities Study has also fielded surveys that include the TSI in Grand Rapids, Flint and Ypsilanti. Johns Hopkins researchers running the Baltimore Area Survey have done the same.

It is our hope that the TSI gets incorporated into more recurring, national surveys. Not only would this allow us to track the ebb and flow of these issues at the national, state and local level, but it would also help us identify geographic hot spots where transportation insecurity is clustering in ways we may not be seeing with other measurement tools.