Tom Vanderbilt has written an entertaining and scary analysis of why people drive as they do. In Traffic: Why We Drive the Way We Do (and What Its Says About Us), he makes the point that it is crazy to accept the rate of carnage on the roads, particularly of pedestrians and bicyclists, but also that it is surprising how well the roads do work. He states that the three greatest contributors to crashes are speed, distraction, and human psychology.
Speed is the defining characteristic of the way we drive, or at least would if we could. The survival rate declines quickly with increasing speed, and this is especially so for bicyclists and pedestrians, where the likelihood of dying in a crash goes up exponentially with speed. At 20 mph, there is a decent rate of survival. At 40 mph, virtually no chance.
Driving is really quite a complex activity, so much to pay attention to all at once, but we as drivers make it even harder by really not paying much attention unless something is out of the usual. We are adapted to direct communication with other humans, but anonymity and speed of driving makes that nearly impossible. We don’t get feedback on our bad driving habits, other than the finger or horn which doesn’t often communicate the necessary information, unless they are so bad that we crash. Otherwise, we tend to assume we are doing just fine, even though we are likely not.

Though everyone has opinions about what causes traffic congestion, very few people (who haven’t read the book) actually do know, and what they don’t know or think they know that is incorrect is responsible for much of the congestion and nearly all of the crashes. He brings in research and anecdotes from all over the world, some about traffic but much about systems theory. Drivers make decisions that may be contrary to their own interests, and quite often make decisions that are contrary to the interested of the system. The result is more congestion and more danger.
Vanderbilt builds quite an effective case that making cars and roads safer does not significantly reduce the crash or fatality rate because people “soak up” that buffer of safety by driving faster and more recklessly, in order to actually maintain the same degree of risk.
People who are unsure that they are safe tend to slow down and pay more attention. That is why roundabouts are actually much safer than signalized intersections – the uncertainty of merging leads to safer behavior. Similarly, removing traffic signs as has been done in some towns in Europe causes people to drive more safely because each driver has to pay attention and use common sense. It converts a “traffic world” built for cars into a “social world” in which people must interact and negotiate. In fact the removal of signs may the the most effective traffic calming strategy available.
Though I don’t drive much, Vanderbilt’s book made me realize how easily I go on autopilot, just like other drivers. I’m very tolerant of the minor mistakes drivers make but become outraged at the big mistakes. It makes me glad I don’t drive much in traffic. The biggest take-away for me, though, is slow it down! Slow down my own driving. Slow down the speed of traffic. In places where traffic is slow, there are few crashes and almost no fatalities. Wouldn’t that be a great world in which to live? Why do we, all of us, accept the carnage as somehow necessary?
Traffic: Why We Drive the Way We Do (and What Its Says About Us)
Tom Vanderbilt
New York: Alfred A Knopf, 2008
ISBN 978-0-307-39772-0
Vanderbilt has a companion website and blog at http://tomvanderbilt.com/traffic/. The Carson City Library has one copy of the book, and I’m returning it today, and there are three more in the state system.