Showing death tolls on road signs could cause more crashes, new study finds

Iowa Department of Transportation signs in January 2017 on Interstate 380 in Cedar Rapids give the final count of road deaths in 2016. So far this year, road deaths in Iowa are up from the same period last year. (The Gazette)

Posting fatality counts on road signs — something the Iowa Department of Transportation has been doing since 2013 — doesn’t reduce crashes and may actually increase them, according to a new study.

Messages on electronic signs are designed to urge motorists to correct bad behavior and drive safer, but they can distract the driver’s attention from the road, said Joshua Madsen, an assistant professor of accounting and traffic expert. behavior at the University of Minnesota, co-author of the study. published last week in the journal “Science”.

“What’s the cost of the two-second distraction?” Madsen said in an interview with The Gazette. “If you’re navigating a complicated section of road, with lots of cars around you, two seconds can be the question of life or death.”

Madsen and Jonathan Hall, an assistant professor of economics at the University of Toronto who studies transportation, analyzed 844,939 crashes within a 10-kilometer radius on the road of electronic signs in Texas from 2010 to 2017.

Texas consistently posted the death toll messages for one week of every month on 880 signs across the state, so the researchers were able to compare the weeks the messages were posted to the weeks they didn’t. were not. Madsen and Hall compared the same times and days of the week, also controlling for weather and holidays.

What they found was that accidents increased by 1.35% when the number of road fatalities was displayed. They also concluded that crashes increased more when the death toll was higher.

Posts that didn’t include the death toll didn’t seem to have much effect, but more studies are needed, Madsen said. He and Hall wrote to the 28 states that post death tolls on electronic signs to see if they wanted to partner with further research, but have not heard back so far, Madsen said.

The Iowa DOT has been posting emails since August 5, 2013, as part of the Zero Fatality Campaign. Iowa has 78 dynamic bulletin boards that span the roads.

Every Friday, the Iowa DOT releases a new safety message that includes a running total of road deaths so far in the year. He also shares the information on Twitter and on a blog.

Some of the roadside messages that have appeared over the years include:

  • Tailgating is for football, not the highway
  • Taxes can wait. So can this text
  • If you got a super bowl, don’t drive high
  • Get your head out of your apps. Drive carefully.

“The goal of our message is not to be funny – the goal is to present a road safety message in a way that is memorable and sticks with drivers,” the Iowa DOT spokeswoman said. , Tracey Bramble, in an email Wednesday. “This could include the use of humor, pop culture or holiday references, emotional appeals, etc.”

But the death toll is sobering. On Wednesday, Iowa recorded 82 road deaths this year, up 24% from the same time last year. Iowa recorded 354 road deaths in 2021, despite an effort to keep that number below 300.

The Iowa State Patrol noted that speed – sometimes at 100 mph or more – is a major factor in the rise in fatal crashes.

The Iowa DOT has seen Madsen and Hall’s study as well as other research on the effectiveness of email messages, Bramble said.

“This is a single study that focuses on one location,” she said. “To our knowledge, we are not aware of any other study that has been able to replicate the results in any other location.”

Bramble said the Iowa DOT has done spot checks of speed data for locations around message boards on days the messages are posted and found no “noticeable decrease in speeds.”

“Furthermore, in the 8 1/2 years of delivering these messages, we have never heard of our messages being a contributing factor to an accident,” she said.

Other researchers have said the subject deserves more attention.

“It’s counterintuitive, but the analysis is solid,” said Gerald Ullman, a transportation engineer at Texas A&M University, College Station, who wasn’t involved in the study but wrote an insight published alongside it. under study, reported Science. Ullman told Science he doubts drivers treat large and small fatalities differently.

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