Displaying highway fatality data on message boards in Texas increased the number of crashes by 4.5% over the 6.2 miles following the message boards, according to new research from the University of Toronto and University of Minnesota.
This increase is comparable to raising the speed limit 3-5 mph or reducing highway troopers by 6-14%, according to previous research.
The goal of highway message death tolls such as “385 deaths on Missouri roads this year” is to get drivers to slow down and focus on the road. But the latest research indicates that this form of “awareness campaign” is actually contributing to distracted driving.
The researchers selected Texas as their test case. In the Lone Star State, officials display fatality messages only one week each month. The researchers compared crash data from before the campaign (Jan. 2010 – July 2012) to after it started (Aug. 2012 – Dec. 2017) and examined the weekly differences within each month during the campaign.
The findings are counterintuitive to the goal of the awareness campaign. There were more crashes during the week with fatality messaging compared to weeks without it.
Specifically, the findings suggest fatality messages cause an additional 2,600 crashes and 16 deaths per year in Texas, costing $377 million each year.
Moreover, the researchers suggest this “in-your-face” messaging approach weighs down drivers’ “cognitive loads,” temporarily impacting their ability to respond to changes in traffic conditions. That’s because driving on a busy highway and having to navigate lane changes is more cognitively demanding than cruising a straight stretch of empty highway.
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 researchers said.
Also noteworthy, the research team found the bigger the number in the fatality message, the more harmful the effects. The number of additional crashes each month increased as the death toll rose throughout the year, with the most additional crashes occurring in January when the message stated the annual total.
They also found that crashes increased in areas where drivers experienced higher cognitive loads, such as heavy traffic or driving past multiple message boards.
However, there was a reduction in crashes when the displayed death tolls were low and when the message appeared where the highways were less complex. This suggests that at times the messaging was not as taxing on drivers’ attention.
Highway fatality messaging has been used in some 27 states.