Share the Road

Share the Road

Traffic: Why We Drive the Way We Do (and What It Says About Us)
Tom Vanderbilt
Knopf, $24.95 

Mental Speed Bumps: The Smarter Way to Tame Traffic
David Engwicht
Envirobook, $23.00 

The High Cost of Free Parking
Donald Shoup
Planners Press, $59.95

When my wife and I visited Lebanon in 1998, we rented a little Renault and spent a couple days on the road, and saw one working traffic light the entire time. The streets of Beirut were packed with a chaotic tangle of aggressive, pushy cars, and I was sure we’d hear steel shrieking on steel the moment we rolled off the car rental lot. We safely got out of the city, and while driving on the winding, two-lane Damascus Road in the foothills of the Chouf mountains, we found ourselves driving next to another car, each going at a good clip. Just then, a third car roared between us, making its own lane. I realized at that point on Lebanon’s roads, all bets were off. And yet, for the rest of our visit, I became more and more convinced that this was one of the safest places I’d ever driven: It was predictably unpredictable.

The time many of us spend getting from one place to another comprises most of our interactions with fellow citizens; it is as much a social experience as anything else. Since time in the car shapes our impressions of each other and of our cities, it might explain the appeal of Tom Vanderbilt’s Traffic: Why We Drive the Way We Do (and What It Says About Us).


Vanderbilt adroitly navigates a mountain of findings and opinions from traffic engineers, economists, psychologists, and even entomologists. Like an excited and precocious teenager, he parenthetically mentions one psychological study while describing another, adding, “more on that later.” But far from being overwhelmed, the reader is swept up in his enthusiasm.

Traffic is the latest in a series of books like Freakonomics and The Tipping Point that draw on diverse and sometimes arcane academic fields to create a coherent narrative for the lay audience. But I hope Vanderbilt will reach more than the casual reader: Planners, architects, and policymakers would do well to read his book.

Perhaps Traffic can best be summed up by one of its innumerable takeaways: You don’t drive as well as you think you do. And if you knew this, you’d drive better. But we don’t even know what we don’t know. That Rumsfeldian quip alone sums up so much about how we behave on the road that awareness of it on our part would make us safer as motorists, cyclists, and pedestrians. Also, awareness of behavior among the people who design our roads and set transportation policy could change our cities for the better. Traffic engineers—who, for the most part, do not appear to be familiar with many of the psychological studies cited in Traffic—try to make our roads safer with more signage, wider lanes, shoulders, and gentler curves. But a growing number of dissidents are pointing out that a safe environment, surprisingly, is one that appears to be dangerous, because it forces us to be more attentive.

The idea that the perception of danger is good for us runs counter to standard reasoning in road design, which argues that since people will make mistakes, the road should provide a comfortable margin of error. This is generally thought to have worked well on highways and arterials, but in cities and towns where different types of users vie for a share of the same space, designing a margin of error into a road for the benefit of motorists is dangerous. They’ll just typically drive faster around that turn, and they’ll be less attentive in that wider lane. To paraphrase the late Hans Monderman, a Dutch traffic engineer whom Vanderbilt interviews, when you treat people like idiots, they will behave like idiots.

Monderman also features prominently in David Engwicht’s Mental Speed Bumps: The Smarter Way to Tame Traffic, a slim and entertaining read that, while nowhere near as broad in its scope as Traffic, is nonetheless insightful. Engwicht, an Australian traffic consultant whom Vanderbilt discusses, had grown increasingly frustrated with the standard traffic-calming measures like speed bumps, neckdowns, and chicanes, and began to develop strategies to deal with aggressive driving in a completely different way. Rather than use negative stimuli to get people to slow down, he argues for positive stimuli—intrigue, uncertainty, and even humor—to engage motorists in their social environments. In other words, pull motorists out of the “traffic world” and into the “social world”—make them interact with each other and with others on the street via eye contact.

In Mental Speed Bumps Engwicht describes how, in his work with neighborhood groups all over the world, he advocates that everyone reintroduce the social world to their streets: bring their chairs outside into the car’s realm, and let their kids play there. In one city, a traffic engineer insisted that cones be placed in the center of the street to separate vehicle traffic from the neighbors socializing and playing, and that signs be erected to warn passing motorists. “It was without doubt the most dangerous street event I have ever conducted,” Engwicht writes, because “the signs and cones were a [false] promise of predictability and certainty.”

The streets of New York City display engineers’ best efforts to introduce predictability for motorists into a town rich in intrigue and uncertainty. They seem always to be fighting an uphill battle: There is nothing to be done about falafel guys pushing their carts in the streets, or brooding hipsters jaywalking while glued to their iPhones. Unfortunately, some of New York’s long-standing policies reinforce the misguided efforts of traffic engineers, and are pulling us out of the social world and into the traffic world. As Donald Shoup observes in his excellent book, The High Cost of Free Parking, the off-street parking minimums that city planning departments require of builders wildly distort the transportation market and wreak havoc on the public realm and on real estate development. The transportation market is distorted because motorists receive a benefit at low cost, subsidized by everyone. When presented with free goods, we consume them.

A professor of urban planning at UCLA and an economist by training, Shoup, who is also profiled in Traffic, is an engaging and passionate thinker, and The High Cost of Free Parking, while it looks thick enough to stun an ox, is as entertaining as it is informative. The book pulls the curtain aside, revealing all the parking space calculations for what they are: best guesses, often padded, and often based on just a single survey of actual conditions. Or, as Shoup says, “pseudoscience.” This pseudoscience is driven by the notion that parking lots should be able to handle peak demand. A Toys R’ Us parking lot has to accommodate shoppers the day after Thanksgiving. But what about the other 364 days of the year?

Parking is essential to transportation in any city. As Shoup points out, though, “food also produces enormous benefits, but this does not mean that we need more food, or that food should be free.” Economists, Shoup says, “do not define the demand for food as the peak quantity of food consumed at free buffets where overweight diners eat until the last bite has zero utility. Nor do economists, when asked for policy prescriptions, recommend that restaurants should be required to supply at least this quantity of free food no matter how much it costs. Yet planners do define parking demand as the peak number of spaces occupied at sites with free parking, and cities do require developers to supply at least this number of parking spaces, whatever the cost. Planning for parking is planning without prices.”

This might seem irrelevant to New Yorkers, whose neighborhoods are more likely to have parking maximums than minimums; however, there are a surprising number of minimums in place, especially for new development. Even plans for dense areas of New York—Hudson Yards, Willets Point—include shockingly high numbers of parking spaces. As Shoup argues, parking not only meets demand, it fuels it.

Traffic, Mental Speed Bumps, and The High Cost of Free Parking are all testaments to the complexity and centrality of social interactions and behavioral economics to our public lives and the fabrics of our cities. Drawing primarily from observations about psychology and economics, these authors show us that what characterizes our cities is much more than an aesthetic experience, traffic flow, or standard land-use metrics. The best urban thinking is done by those who truly observe and understand how we behave.