When traveling at high speeds on busy highways, drivers are sometimes overwhelmed by a myriad of different roadside signs, such as speed limit signs, directions to prominent landmarks, and safety warnings. But worryingly, a new study finds that at least some roadside safety warning signs can backfire, leading to more fatal crashes rather than fewer.
Like many U.S. states, Texas displayed dynamic warning signs on giant digital billboards indicating recent traffic fatalities, such as “1,669 deaths on Texas roads this year.” But unlike other states, Texas displays the sign only once a week per month, providing an opportunity to compare the evolution of crashes between two different groups of drivers — those who were exposed to the sign and those who weren’t. People who have been exposed to this sign. In most other states, these feed symbols are more or less random, following unpredictable patterns. It’s unclear why the Texas Department of Transportation chose this timeline, but the researchers are grateful because it provides the ideal setting for a natural experiment.
Joshua Madsen, an accounting professor at the University of Minnesota, and Jonathan Hall, an economist at the University of Toronto in Canada, pooled data from nearly 900 dynamic message signs in Texas, then set out to analyze traffic accidents that occurred after exposure to such messages.
When the results finally started to come in, the researchers were simply stunned.Not only do these flags not work, but they also work with Increase The accident rate within 10 kilometers downstream of the message board is about 4.5%.
The study found 2,600 additional accidents and 16 fatalities per year in Texas, with an estimated annual socioeconomic cost of $377 million. Another way of looking at it is that the result is equivalent to raising the speed limit by 3 to 5 mph (4.8 to 8 km/h) or reducing highway policing by as much as 14%.
The underlying hypothesis on everyone’s mind is that these sobering messages should make people more aware of their surroundings, thereby helping them drive more carefully. So what could explain these findings?
No clear explanation can be drawn from the way this study was designed, but the authors have some thoughts.
They argue that passing the news of a traffic fatality is sure to get the attention of drivers, but not in the way authorities would like. Instead, these stark warnings may lead people to question their own mortality, into a sort of mini-existential crisis. The end result is that they become extremely distracted by their own tangled thoughts, increasing the risk of an accident and possibly making insurance so expensive.
Another explanation is that some people may indeed be getting the correct message that they need to drive more safely, but end up doing more harm than good by undercompensating, e.g. when another car is in front of them, they drive more safely than usual. Brake hard. Or it could just be another example of information overload, and on some highways, these signs, along with dozens of other warning signs, can be enough to overwhelm drivers.
However, Madsen firmly believes that the fear of death may be the main reason for the rise in traffic accidents. His data set showed that as the number of traffic fatalities displayed on the display increased (the counter resets to zero at the beginning of each year), the risk of an accident downstream from the sign also showed a perfect linear relationship. “The higher the number shown, the more crashes there were in that month,” he said. The larger the number of deaths on the warning signs, the more dire they are, so people are more likely to start thinking about their fragile existence and what if they share the same fate as their loved ones?
Gaining insight into this problem is very challenging, and perhaps the only way to reveal its mechanism of action is to study the brain waves of volunteers when they encounter pathological road signs as a vehicle simulator. But if there’s an important takeaway, even seemingly good ideas can backfire. People analyze information all the time, and the lesson is that authorities need to be very careful about the information they choose to present.
The research results are published in the journal science.