Displaying Death Tolls on Highways Isn’t Making Anyone Drive Any Safer
(Source: Flickr/Jonathan Cutrer.)
Signs reminding drivers of the dangers of driving are a common sight across the country’s roads. Some encourage vigilance while others broadcast fatality rates. One study, however, found that these behavioral interventions not only fail to produce safer driving environments, they may actually induce more crashes.
According to the study, behavioral interventions—sometimes called nudges—have become a popular way to encourage “socially desirable behaviors.” Over 200 governments and institutions worldwide have implemented some sort of nudge in the hopes of influencing behaviors as varied as caloric intake, hand washing, and, of course, driving. While these interventions take shape in many forms, the study observes that they are often “expressly designed to ‘seize people’s attention’ at a time when they can make the desired action.” In other words, timing is key.
On roads, however, timing can be hazardous. In Texas (where the study was focused), installing signs displaying death tolls involved little consideration of individuals’ cognitive restraints, “and the possibility that seizing one’s attention may crowd out other, more important considerations.”
As a result, the study found a correlation between times when the nudges were broadcast and an increased probability of crashes. During weeks when TxDOT displayed death tolls, crashes went up 4.5% over a 10-kilometer (6.2-mile) distance compared to weeks without the messaging. “The effect of displaying fatality messages is comparable to raising the speed limit by 3 to 5 miles per hour or reducing the number of highway troopers by 6 to 14%,” the study added.
Its five key lessons showcase other reasons that Texas’s nudges are likely ineffective:
Individuals don’t necessarily habituate to behavioral interventions, even after years of treatment.
The effects of interventions do not necessarily persist after treatment stops.
These inferences suggest that even if successful in the short term—which the study demonstrates isn’t even the case—there aren’t proven long-term benefits to these shame and scare tactics.
Nevertheless, campaigns like the ones in Texas have spread to over 28 states since 2012. They’re popular because of their relative ease of implementation and low cost. For example, in Texas, the Department of Transportation used existing dynamic messaging signs rather than investing in new equipment.
At the same time, if we consider their inefficacy (or worse, their ironic side effects), the costs, both socially and economically, are much larger. The study calculated that the 4.5% increase translates to 2,600 crashes—including 16 fatalities—with a cost of $377 million per year. Luckily, there are proven ways to engineer safer driving and it starts with street design.
“The way we nudge people to safer roads isn’t to change their thinking,” said Strong Towns President and retired engineer Chuck Marohn. “It’s to respond to their behavior.”
Marohn argues that, rather than gambling on minimizing human error through marketing campaigns, departments of transportation should acknowledge human error as inevitable and design streets with that in mind. To an extent, DOTs already do this with wide lanes, clear zones, and other features. He points out, however, that rather than compensate for human error, those features provide drivers with a “false sense of security, one that speed studies demonstrate induces them to drive faster.”
Acknowledging human error—or nature—by contrast, would involve designing streets less conducive to speeding and other behaviors that increase the likelihood of a deadly crash. That can look like narrower lanes, street trees, tightened curves, and so on. “If we really want to nudge drivers to behaviors that improve safety, we do so by designing streets so that drivers feel insecure,” Marohn proposed. “So they have a feeling of tension and anxiety, when they are driving at speeds that are unsafe for that environment.”
Today, when a crash occurs, officials, insurance companies, and the public focus on who was at fault, rarely taking the design of the area into consideration.
When a crash occurs on the same street multiple times a year—or even a month—it’s worth asking how the built environment caused those involved to err. Why couldn't they navigate this place safely? What can we change about this street or intersection to make it safer?
These are exactly the questions the Strong Towns Crash Analysis Studio is asking. We’re analyzing real crashes in your neighborhood with a panel of experts and locals in order to determine how the design of the street contributed to the tragedy. If we want safer streets, we need to change our standard of care whenever a crash makes the headlines.
Be a part of this shift. The next Crash Analysis Studio is taking place August 25, 2023, at 11:45 a.m. Central. Sign up to attend here.
Designing streets to encourage safe behavior is a powerful tool for creating lasting prosperity. But when cars are designed to encourage unsafe behavior, it threatens to undo that progress.