Traffic

Just before holiday break*, I came across an interesting-looking book in the library catalog, while I was helping a student locate something else for her research. So I spent part of the break reading Tom Vanderbilt's Traffic: Why We Drive the Way We Do (and What It Says About Us). And lo and behold, suddenly I come cross a blog entry about the same book at Cognitive Daily, complete with this interesting video of Parisian drivers negotiating the ridiculously unorganized intersection at the Arc de Triomphe.


Paris Traffic from Dave Munger on Vimeo.

David Munger describes the book pretty well, so I won't rehash it all here, but I did want to expand on his discussion of the confusing traffic circle. Vanderbilt describes how a cognitive shift takes place when the traffic engineers start adding or removing safety barriers and curbs, or reducing the width of the right of way. Moving buildings and sidewalks farther from the street, for example, would seem to enhance safety, but there is a countering tendency for drivers to think of the street as a highway** and drive as if the surrounding city weren't there. Or more precisely, they are quite aware that the road has been given priority and they drive on the assumption that everyone else agrees.

But when you start moving things back close to the street, maybe even eliminating curbs and crash barriers, the driver becomes more aware of the city and even a little confused. Who has been given priority, the cars or everyone else? Whose turf is he on? And he slows down and pays much closer attention to what's going on around him. Arguably, this is a safer frame of min for the driver to be in, rather than whizzing down the street assuming that everything off to the side can be ignored.

That same sort of cognitive shift was also at the heart of what I always thought was wrong with traffic in Yellowstone. For us employees, the roads were roads, those strips of asphalt that connect the place where I am with the place I would prefer to be. You drive on them. For tourists, though, it always seemed to be a little different. Sure, you drive on these roads, but you also creep down them at ten miles per hour, or stop, or even park in the lane and leave your vehicle. Things you would never do on any road at home, but in the Park it was just different. In the same way that people don't take lane markings seriously in a parking lot, tourists in Yellowstone took all the familiar signs and markings as vague suggestions. I came to believe, for example, that the real definition of intersection was "a place to stop and read your map."

It's a testimony to the power of categorization. The whole category of behavioral rules that go along with roads suddenly disappeared, because the drivers didn't conceive of the Yellowstone roads as roads in the normal sense. As soon as they left the Park, normal behavior returned; you rarely saw the same type of driving in the National Forest lands surrounding the Park. Those had roads, you know, with highway designations and everything***. Totally different.



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* Christmas break, for those who get worked up about such things.

** And the significance should be evident from the fact that we use two different words, street and road, to decribe the same object in different contexts.

***Technically, there are several US highways running through Yellowstone: 191, 287, 89, 20, 14, and 16. You won't see a sign for any of them inside the Park boundaries, though. I wonder what difference it might make in driver behavior if the signs were there?