Our sense of what's dangerous on the road is not always accurate, according to author Tom Vanderbilt.

As Vanderbilt tells NPR's Steve Inskeep, "The classic case of risk perception being wrong" in traffic is drivers' anxiety about driving in a traffic circle, or roundabout, as opposed to driving through an intersection with a stoplight.

"People fear roundabouts in America — they've been called 'Circles of Death,' Vanderbilt says. "And nothing could be further from the truth."

The geometry of a roundabout eliminates one of the most dangerous moves you can make in driving: a left turn against fast-moving oncoming traffic. Also, since traffic circles involve a lot of other drivers and a driver is not relying on signs and symbols, drivers must make their own decisions and be aware of other traffic.

If that sounds stressful for drivers, Vanderbilt says a little stress might not be a bad thing. "I think they tend to act more cautiously, which is a positive result," Vanderbilt says.

Texting on a mobile device has recently emerged as one of the most dangerous hazards on the road. Vanderbilt calls it the "perfect storm" of distraction for drivers.

"It brings a visual distraction, a mental distraction and a tactile distraction all at once, which is something no other technology does," he notes.

Talking on cell phones is perhaps the next-worst culprit. But even more mundane things — a child in the back seat of the car crying, for instance — can take a driver's eyes, and perhaps his mind, off the road.

As for other distractions, Vanderbilt hesitates to blame the radio — particularly certain networks.

"Listening to radio — especially public radio! — can be a good thing in the car," he said. "It keeps your mind alert and keeps you engaged."

Vanderbilt says that decades ago, the idea of playing a radio while driving was controversial, with some questioning whether radio might distract drivers and lead to crashes. While Vanderbilt says studies have refuted that, he notes that radio dials can present a certain hazard — which is why some carmakers have moved them up to steering wheels.

Still, new laws and helpful technology have their limits. They can't do much to force a driver to concentrate, for instance.

"This is something you can't really legislate," Vanderbilt said. "You can't ask people to not daydream. We're human. We're not robotic devices that can maintain 100 percent vigilance."

Vanderbilt once had a minor accident as a teenager because he was distracted by tuning the radio, on a drive from Madison, Wis., to Chicago. The crash provided him with a constructive form of feedback about his attitude behind the wheel — something many drivers don't get.

"In situations where we don't have a lot of feedback, overconfidence tends to really bloom," Vanderbilt said. A classic psychological problem with driving, he says, is the "Lake Wobegone" effect.

"You ask a big group of people, 'Who here is an above-average driver?' and 100 percent of the people raise their hands," Vanderbilt said. "It's statistically impossible to find any below-average drivers. They're out there, but they don't own up to it."

Vanderbilt says that in road safety, human nature is the X factor. Cars have become safer and roads have been made safer over the decades, but he doesn't think that has led to better driving.

In fact, he says, mobile devices in cars may have led to a decline in drivers' skills. "So road safety has improved in spite of the driver, not because of the driver," Vanderbilt said.

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