Enlarge By Robert Deutsch, USA TODAY Watching for signs ahead: Tom Vanderbilt, driving in Brooklyn, N.Y., has written Traffic: Why We Drive the Way We Do (and What It Says About Us).  SOME SURPRISING, UNWRITTEN RULES OF THE ROAD In Traffic, Tom Vanderbilt compiles facts and studies about cars, their drivers and the way they drive: The average American spends 38 hours a year stuck in traffic. So much time is spent in cars that drivers (particularly men) have higher rates of skin cancer on their left side. In the 1950s, about 40% of daily car trips had to do with work. Now, the average is 16%. People aren't making fewer trips to work; they're driving to so many other places. In the past four decades, the daily distance driven by the average American rose from 21 miles to more than 32 miles. In 1969, nearly half of American children walked or biked to school; now 16% do. The size of the average American family has fallen over the past several decades, but the number of multi-car garages has almost doubled: One in five new houses has a three-car garage. Men honk their horns more than women; men and women honk more at women; drivers in cities honk more than people in small towns; and drivers are more reluctant to honk at drivers in nice cars. At shopping malls, drivers who look for the "best" parking spot spend more time getting to the store than people who simply take the first empty spot they see. Drivers think small cars are farther away than they actually are. Drivers seated at higher eye levels, such as those in SUVs or pickups, are more likely to drive faster than drivers at lower heights and are more likely to underestimate their speeds. Drivers take longer to leave a parking spot when another driver is waiting. Fast-food restaurants attract as much as 70% of their sales at drive-through windows.

Three years ago, Tom Vanderbilt, 40, a magazine freelancer who writes about design and technology, was driving on a crowded New Jersey highway when a sign loomed: LANE ENDS ONE MILE: MERGE RIGHT.

His first impulse was to immediately do what the sign said. Instead, he told himself, "Don't be a sucker. You can do better."

He zoomed ahead without changing lanes, despite hostile stares from stalled drivers to his right. He made it to the bottleneck, merged late and found an open road ahead.

Later, he asked himself, "Was I wrong to have done this? Why should one lane move faster than the other? And why are people rewarded for merging at the last possible moment?"

Behind the wheel of his 7-year-old Volvo on the streets of his Brooklyn neighborhood, Vanderbilt isn't just the author of a 402-page non-fiction book subtitled Why We Drive the Way We Do (and What It Says About Us), out today.

He's also a driver who likes to discuss how he became a "late merger," why "slower is faster," and why ants never get into traffic jams, like the one this afternoon on the Brooklyn-Queens Expressway, which, as often happens, isn't living up to the last part of its name.

Vanderbilt is reminded of something "the late, great" Henry Barnes, a traffic commissioner in Baltimore, Denver and New York, once said: "Traffic is the mother-in-law in the otherwise perfect romance between Americans and their automobiles."

In Traffic (Knopf, $24.95), Vanderbilt writes that he lives in "the most auto-dependent, car-adapted, mileage-happy society in the history of the planet."

But how much will $4-a-gallon gasoline change that?

"It's hard to know whether this is a short blip or whether, in a decade, we'll all be driving Teslas, which consume much less energy and thus would conceivably promote more driving," he says.

"For now, though, train ridership is booming, Ford's pickup plants are being closed, and even the mayor of Houston's talking about mass transit. It looks a bit different out there than when I started the book."

It's complicated

Traffic got into gear after that merging epiphany in New Jersey. Vanderbilt posted an anonymous inquiry on Ask MetaFilter, a website designed to tap into an audience of what he calls "overeducated and over-opinionated geeks."

Vanderbilt was startled by a torrent of passionate responses equally divided over whether he had rationally used the highway's maximum capacity or selfishly added to the traffic problems.

With a little more research, he found an "entire literature" on the science and psychology of merging and began work on a book that isn't only about "the traffic signals we obey, but also about the traffic signals we send."

His research took him to New Delhi, renowned for its disobedience of traffic rules, and to the Netherlands, which has found that fewer traffic signs and signals make for safer roads.

He interviewed psychologists and engineers, and he visited Los Angeles' "traffic bunker" on Oscar night, when special traffic patterns are created so the stars' limos can get to the red carpet on time. (That year's winning movie was Crash, which is about "L.A. traffic on literal and metaphorical levels.")

Much of what he learned was counterintuitive, he says.

Consider, for example, the feared roundabout. It starred in National Lampoon's European Vacation when an American family, having driven into a London traffic circle, finds they cannot leave, orbiting endlessly.

In real life, studies show well-designed roundabouts are safe and reduce traffic delays.

"The system that many of us would feel is more dangerous is actually safer, while the system we think is safer is actually more dangerous," he says.

That is because intersections are what he calls "crash magnets," the site of half of all traffic collisions.

Engineers calculate that a four-way intersection has 56 potential points of what they call "conflict," or as Vanderbilt says, "the chance for you to run into someone" — 33 places to hit a car and 24 spots to hit a pedestrian.

Roundabouts, on the other hand, reduce the number of potential conflicts to 16. They reduce speeds and prompt drivers to pay more attention to what they're doing, rather than simply sailing through a green light.

Or "the system that makes us more aware of the potential danger is actually the safer one."

But don't roundabouts slow traffic?

That, Vanderbilt says, depends on how you look at it. A driver with a green light makes better time than a driver who has to slow for a roundabout. But "roughly half the time, the light will not be green."

"Slower is faster," Vanderbilt likes to say, noting how traffic lights can be timed to enable drivers going at a certain speed to hit a line of "constant greens."

Driving faster means having to stop at the next red light, which requires deceleration and acceleration, which, in turn, costs time and fuel. Engineers call it "start-up lost time," which strikes Vanderbilt as "an appropriately forlorn echo of Proust."

Among his other findings:

•Merging, as when three lanes become two, is "the most stressful single activity we face in everyday driving."

Late merging makes the most sense but only when every driver does it and takes his or her turn, "which isn't always the case."

•Army ants are among the world's most efficient commuters for a simple reason: "They're all co-operating."

Animal behaviorists have made videos of ant trails that show what appear to be three-lane highways with well-defined, collective rules.

Humans "want to assert our individuality or our sense of superiority on the road, but as everyone does that, it makes it worse for everyone."

•Driving is, "for most who are not brain surgeons, probably the most complex everyday thing we do in our lives," which is why robots, so far, make lousy drivers.

But driving also is what psychologists call an "overlearned" activity — something we're so well practiced at that we're able to do it without much conscious thought.

And it's "when we forget that driving isn't necessarily as easy as it seems to be, we get into trouble," he says.

We're all A.J. Foyt now

Surveys show most drivers think they're above average, which is statistically impossible, and it is the other drivers who cause problems.

Vanderbilt says psychologists who measure narcissism in American culture are finding more people who say things like, "If I ruled the world, it would be a better place."

Such thinking results in traffic "filled with people who think that roads belong only to them … that being inside the car absolves them from any obligation to anyone else."

Vanderbilt works from home, doesn't face a daily commute and does much of his driving on weekends, favoring country roads to city traffic.

Having studied how complex driving is has made him a better, more cautious driver, but he fears he's becoming "a safety bore."

His biggest fear is that the author of Traffic will cause a traffic accident. He doesn't expect to do much driving on his 10-city book tour, from New York to Los Angeles, in the next two weeks.

He'll be flying, which, of course, presents its own kind of congestion.

TELL US: What's your biggest traffic gripe? Leave your comments below.