Highway Death Toll Messages Found to Cause More Crashes

ALEDO, Texas — The message is clear. Roadside safety messages intended to prevent highway accidents were found instead to contribute to the number of crashes along road segments.

Researchers from the University of Minnesota’s Carlson School of Management and the University of Toronto’s Munk School of Global Affairs and Public Policy studied the effect of displaying crash death totals on highway message boards installed by the Texas Department of Transportation. Their findings suggest that the weeks in which TxDOT’s messages were displayed there were more crashes, not fewer.

“Driving on a busy highway [and] having to navigate lane changes is more cognitively demanding than driving down a straight stretch of empty highway,” Joshua Madsen, UM assistant professor of accounting and co-author of the report, said.

“People have limited attention. When a driver’s cognitive load is already maxed out, adding on an attention-grabbing, sobering reminder of highway deaths [can] become a dangerous distraction.”

The TxDOT messages were consistently displayed only one week each month prior to the agency’s monthly board meeting. The researchers used data on 880 dynamic message signs and all crashes that occurred in the state between Jan. 1, 2010, and Dec. 31, 2017, to investigate the safety campaign’s effects.

The researchers estimated whether the chosen weeks for the messages inherently differed by using data from before TxDOT started displaying fatality messages and data from upstream message signs to account for a placebo effect. 

In their findings, the researchers conclude there were more crashes during the week with fatality messaging compared with weeks without the messaging. They also note that displaying a fatality message increased the number of crashes by 4.5% over the 6.21 miles following the message boards, and that fatality messages cause an additional 2,600 crashes and 16 deaths per year in Texas.

“The messages also increased the number of multi-vehicle crashes, but not single-vehicle crashes,” Jonathan Hall, assistant professor of economics at Toronto University and co-author of the study, said in a written statement. “This is in line with drivers with increased cognitive loads making smaller errors due to distraction, like drifting out of a lane, rather than driving off the road.”

The findings suggest the “in-your-face” messaging style of the safety campaign hampers drivers’ cognitive loads and temporarily impacts their ability to respond to changes in traffic conditions. Consequently, the researchers estimate the social costs of the additional traffic accidents add up to $377 million annually.

Additionally, the researchers observed a reduction in crashes when low death tolls were displayed and when the messages appeared on less complex highways. Different versions of highway fatality messages have been displayed in at least 27 states across the country.

“Distracted driving is dangerous driving,” Madsen said in a written statement. “Perhaps these campaigns can be reimagined to reach drivers in a safer way, such as when they are stopped at an intersection, so that their attention while driving remains focused on the roads.” 

Reece can be reached at [email protected].