Counter-intuitive lessons from the road

Gas prices have fallen as we approach the end of summer. Who could've imagined that?

If you'll pardon my sarcasm, you might find fascination in Traffic: Why We Drive the Way We Do (And What It Says About Us), by Tom Vanderbilt, which gets top billing in today's NYT Book Review:

Vanderbilt cites a statistic that nearly 80 percent of crashes involve drivers not paying attention for up to three seconds. Thus the places that seem the most dangerous - narrow roads, hairpin turns - are rarely where people mess up. "Most crashes," Vanderbilt writes, "happen on dry roads, on clear, sunny days, to sober drivers." For this reason, roads that could be straight are often constructed with curves - simply to keep drivers on the ball.

Rotaries, more common in neighboring Massachusetts, are safer than intersections:

A study that followed 24 intersections that had been converted from signals or stop signs to roundabouts showed an almost 90 percent drop in fatal crashes after the change.

For similar reasons, S.U.V.'s are more dangerous than cars. Not just because they're slower to stop and harder to maneuver, but because - by conferring a sense of safety - they invite careless behavior. "The safer cars get," Vanderbilt says, "the more risks drivers choose to take." (S.U.V. drivers are more likely to not bother with their seat belts, to talk on cellphones, and to not wear seat belts while talking on cellphones.) So it goes for much of the driving universe. More people are killed while crossing in crosswalks than while jaywalking. Drivers pass bicyclists more closely on a road with bike lanes than on one without.