Review of Traffic: Why We Drive the Way We Do…

Psychology is as important as engineering in governing traffic flow

Aug 9, 2009

For any driver who has ever marveled or raged at how easily traffic can turn into a mess, author Tom Vanderbilt uncovers a complex web of mental and engineering factors.

Author Tom Vanderbilt's revelations may not make anyone's commute faster, but they should earn a whole new level of respect for the work done by highway engineers and their ilk. Not to mention the work done by the brain of anyone behind the wheel.

In "Traffic: Why We Drive the Way We Do," Vanderbilt makes a convincing case that traffic flow is far from a precisely calculable matter of speed limits, lane widths and other physical factors. Human behavior is at least as important a factor, and a terribly unpredictable one, given how far beyond evolutionary adaptation everyday driving requires the human mind to work. "For most of us who are not brain surgeons, driving is probably the most complex everyday thing we do in our lives," the author maintains.

Evolution Didn't Equip Humans for Freeway Driving

Start with speed. Basically, the brain and visual system aren’t equipped to deal with anything beyond 20 mph, slightly above the speed of a very fast runner. Require them to work above that speed and the inevitable result is all kinds of errors in positioning, distance estimation and more - i.e, traffic accidents.

The author also notes that evolutionarily, humans are equipped to deal with a total social pool of 100 or so people, at which level every interaction is ripe with significance. Which helps explain why drivers get inordinately peeved when a stranger treats them rudely on the highway and just as inordinately pleased when they encounter courtesy.

Or consider the psychology of parking lots. For anyone who has ever found himself getting irked at another driver waiting to pull into their spot, there's more evolutionary psychology at work. The very fact that someone else is waiting for that space confirms it has value, and humans are hard-wired not to give up valuable things.

Safety improvements lead to riskier driving

At least as fascinating is the idea of "homeostasis or risk," which says that humans have an inherent sense of how much risk they're willing to accept in a certain activity. This is a big part of the reason why, every time a new safety measure such as ABS brakes or banked curves is introduced, accidents sink for a while but then slowly rise back to slightly below the previous level. Drivers are compensating for the new engineering by driving in a slightly more risky way.

Risk assessment also plays a big role in overturning some common wisdom. Vanderbilt argues that traffic signs generally don’t work because they give drivers a false sense of control. The same can be said for those European roundabouts, which turn out to be significantly safer than traditional four-way intersections. Anything that forces drivers to pay more attention to their surroundings is better for safety, the author maintains.

Few of Vanderbilt's revelations are likely to have much immediate impact on improving anyone's driving experience - although he makes a convincing case for putting down the cell phone and chalupa and paying attention to the road. But he will give a whole new appreciation for the dauntingly complex mental exercises motorists confront every day, putting him squarely in the ranks of such pop psychology authors as Malcolm Gladwell and Steven Levitt.

The copyright of the article Review of Traffic: Why We Drive the Way We Do… in Psychology is owned by David Becker. Permission to republish Review of Traffic: Why We Drive the Way We Do… in print or online must be granted by the author in writing.