11.21.2017

The Six Main Causes of Car Crashes—and How to Avoid Them This Thanksgiving

The Six Main Causes of Car Crashes—and How to Avoid Them This Thanksgiving Brian Brainerd/The Denver Post via Getty Images

Car crashes are mysteries. Even though roughly 6 million of them happen each year in the United States alone, we seldom learn much. When we do drive by a crash, we often slow down to have a look. But there’s never much to see. Two crumpled cars. Maybe one upside down. An ambulance closing its doors. I usually feel bad—for those who may have gotten hurt (or worse), of course, but also because my rubbernecking contributes to the logjam of cars behind me.

I want to know what happened because there’s an obvious payoff. I want to make sure that the same thing doesn’t happen to me. Was it some bonehead move that I would never make? Or did someone commit a minor transgression and then pay a major price? Give me an instant replay like I get when I’m watching football. A slow-motion video with expert commentators who draw diagrams and who reveal in explicit detail how it all went down.

Without the details of how crashes happen, we tend to dismiss them as the work of “idiots”—drivers who occupy the lower echelons of driving skill and common sense. But while humankind’s measured intelligence is increasing, so is the number of deadly car crashes. After a lifetime of improvement, we saw an 8 percent jump in crash fatalities during 2015, the largest in 50 years. That number rose again in 2016, when more than 40,000 people died in collisions.

Fortunately, science is coming to the rescue. We no longer have to rely solely on dents, skid marks, and the lawyer-vetted remarks of drivers to figure out what happened and to tell us how to avoid the next crash. In a landmark study published in 2008, researchers at the University of Michigan combed the scene of 6,950 crashes to give us a more detailed analysis of what happened during each crash. Naturalistic driving studies are now equipping cars with accelerometers, sonar, sensors that track driver inputs, and lots of video cameras. Drivers sign up to participate in these studies, and they sometimes crash, leaving researchers with valuable data. We’re also benefiting from the rise of road cams—dashboard-mounted video cameras owned by everyday drivers, aka cammers, who cruise around, record crashes, and then post them on websites like Reddit.

I’ve rolled up the fruits of these efforts to provide a closer look at what the evidence tells us are six of the most common crash scenarios. None of these types of crashes are rare occurrences or the work of the especially incompetent. They happen as a result of simple misunderstandings of what can happen when cars, roads, and minds of even the most intelligent and responsible drivers all come together.

For the full story, visit Slate.com/Technology.