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TxDOT message designed to promote safety backfired according to study

Sign showing the number of deaths on Texas roads
Jonathan Cutrer
Sign showing the number of deaths on Texas roads

TPR's Jerry Clayton recently spoke with Joshua Madsen, co-author of a study which suggests that one particular message shown on electronic signs in Texas actually increased the number of traffic crashes.

Jerry Clayton: The ubiquitous TXDOT electronic highway signs are intended to increase traffic safety. But a new study shows that one particular message increased highway crashes in the state by as much as 4.5%. Here to talk about that study is coauthor Joshua Madsen, assistant professor of accounting at the University of Minnesota. Thanks for being here, Joshua.

Joshua Madsen: You're welcome. Thank you so much for the invitation.

Clayton: Can you tell me why you chose Texas for your study?

Madsen: What's great about Texas is it's a big state. You've got a lot of these DMS's (Dynamic Messaging Signs), a lot of drivers also, unfortunately, a lot of crashes. And as I dug deeper in and discovered, much to my surprise and happiness, that they decided to only show up one week a month, which provided a really valuable variation to figure out how these signs are affecting drivers. Because I could compare and see what was happening in the off weeks when the messages were not being shown.

Clayton: So your study specifically looks at the messages that indicate how many people have died on Texas roadways. Correct?

Madsen: So that is the only one that we truly analyzed in a very rigorous manner. And we needed this variation of they are shown during a specific time period and then they are not shown during another. We do have in the paper where we looked at various other types of messages, but that kind of research design, that analysis is much more suggestive given that you don't have that deliberative showing it now, and I'm not showing it another time because they could be shown, you know, for what we what we call in our in our lingo, endogenous reasons. Right? I'm only showing it at night because there's not a lot going on or I'm not going to show it during more busy times. So for that reason, we don't really focus on many other messages. The real focus is on these fatality messages. And, you know, when I first saw it, I myself was a bit shocked, Jerry. I did a little bit of a double take. I was driving on I-94 in Illinois just trying to figure out where those deaths were coming from or those deaths only on highways or was it state wide across all roads. And so it resonated with me at least, that these things could plausibly be distracting.

Clayton: Your study mentions cognitive overload. Can you explain what that means?

Madsen: We have to basically hypothesize about various mechanisms. We do a bunch of tests, and the one that stands out with the most support, I would say, would be this distraction or cognitive overload. The idea being there's only so many things you can focus on as human beings. We can multitask to a certain degree. But as your attention diverts from one active task to another, you can't process it all at the same time. And so the hypothesis was that perhaps these signs are just grabbing too much attention. And if your cognitive load is already fairly maxed out because you are attentive and focusing on driving, then that portion has to slip something as you are substituting and a focus on deaths and what that number might mean and how I'm supposed to respond, etc..

Clayton: How has the Texas Department of Transportation responded to your study?

Madsen: So I know that they have issued a statement to various requests (see below) suggesting that they appreciate, in my own words, that they appreciate a focus on driver safety, but they believe the main determinants are things like driving too fast and not wearing your seatbelt and distracted driving, which I wholeheartedly agree with, right? This is not the main determinant of crashes and I don't want to intend or claim that it is. Those others are certainly much more important if we can get drivers to slow down and stop texting and driving, certainly I would expect to see a much larger reduction in crashes. The focus of this study, again, was to evaluate a very salient behavioral nudge by providing information at plausibly the wrong time and space and showing that it is, in fact backfiring.

Clayton: Joshua, thank you so much for being with us today. It's a fascinating subject. I really appreciate your time.

Madsen: Thank you so much for your interest, Jerry, and God bless you and God bless the state of Texas.

Statement from TXDOT about the study:

"The real issues around traffic fatalities in Texas are speed, distracted driving, impaired driving and people not wearing seat belts. We appreciate any focus on safety and the critical need to inspire drivers to make the best decisions behind the wheel. In relation to this particular study, there are too many unknowns to draw any firm conclusions, to include assumptions made by the study authors regarding driver psychology and behavior.

We continually evaluate the effectiveness of our safety messages, and for quite some time now, we have not shared fatality numbers on the dynamic messaging signs (DMS). We look for every way to make our roads as safe as possible, and to use effective measures to remind drivers that most of the time they have the power in their hands to help prevent fatalities on our roadways."

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Jerry Clayton can be reached at jerry@tpr.org or on Twitter at @jerryclayton.