TRAFFIC: WHY WE DRIVE THE WAY WE DO, by Tom Vanderbilt, Knopf, 401 pages, $24.95

The author writes articles and books about design, technology, science and culture. In this fascinating book, he analyzes how human nature has shaped traffic and vice versa. Some of the predictable questions he considers include:

• "Why does the other lane always seem faster?"

• "Why do additional lanes seem to intensify congestion?"

• "Whatever happened to signaling for turns?"

• "Can you gauge a nation's driving behavior by its levels of corruption?"

• "Can traffic reporters tell where a storm is heading by looking at traffic patterns?"

Exhaustive research also has taught the author some fascinating maxims:

• Driving aggressively, which raises crash risk and increases fuel consumption, saves only a minute on a 27-mile trip.

• Men honk more than women, and men and women honk more at women than at men. Drivers also honk faster at cars whose drivers are on cell phones.

• More people are killed while legally crossing in crosswalks than while jaywalking.

• Rubbernecking cuts highway capacity by more than 12 percent, on both sides of the highway. Looking at crashes is actually a leading cause of crashes.

The author also considers interesting driving phenomena, such as "Highway Hypnosis" or "Time-gap Experience." He asserts that a great many drivers will reach a certain destination and realize they don't remember driving there. This usually happens, he says, in monotonous or familiar driving situations — but some scientists think that it is related to drowsiness and that some of us may be taking "microsleeps" at the wheel.

According to Vanderbilt, driving is the most complex activity in which those of us who are not brain surgeons engage. That's because it includes at least 1,500 subskills, i.e., navigating through terrain, scanning the road for hazards, keeping our position on the road, judging speed, making decisions, evaluating risk, adjusting instruments, anticipating potential actions of other drivers, thinking about last night's episode of "American Idol," checking voice mail, talking on a cell phone or quieting a toddler.

One study said that a different piece of information is introduced to the driver every 2 feet, which, at 30 miles per hour, means the driver is exposed to 1,320 new bits of information per minute. This is comparable, he says, to reading three paragraphs while looking at pretty pictures, as well as all of the things just mentioned "every minute you drive."

Then there is the problem of traffic engineering, meaning the process of "cutting roads through the social world."

"The traffic world and the social world are shouting at each other," he writes. Utah drivers know about those things because many of our roads have "disappearing lanes," which cause drivers to instantly regroup. Ordinarily, this would be considered a traffic engineering problem, and a major cause of accidents.

For years, traffic engineers have been teaching "passive safety" in road design, suggesting that a driver who makes an error is likely to come to a stop about 30 feet off the road. This means there must be ample "clear zones" to absorb what otherwise would be an accident.

This is a well-written, important book that should hold the interest of anyone who drives a car.

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