Tuesday, August 26, 2008

Traffic calming

I enjoyed this excellent profile of recently deceased traffic engineer, Hans Monderman. His claim to fame is removing traffic signs and mixing cars, bicyclists, and pedestrians, which forces everyone to pay more attention and results in both fewer collisions, and lower impact collisions. It's easy to fall into the "see, regulations are bad" or "we can rely on the good will of others" traps when reading about Monderman's idea, but I think the key graf is this:
As I watched the intricate social ballet that occurred as cars and bikes slowed to enter the circle (pedestrians were meant to cross at crosswalks placed a bit before the intersection), Monderman performed a favorite trick. He walked, backward and with eyes closed, into the Laweiplein. The traffic made its way around him. No one honked, he wasn’t struck. Instead of a binary, mechanistic process—stop, go—the movement of traffic and pedestrians in the circle felt human and organic.

A year after the change, the results of this “extreme makeover” were striking: Not only had congestion decreased in the intersection— buses spent less time waiting to get through, for ­example— but there were half as many accidents, even though total car traffic was up by a third. Students from a local engineering college who studied the intersection reported that both drivers and, unusually, cyclists were using signals— of the electronic or hand variety— more often. They also found, in surveys, that residents, despite the measurable increase in safety, perceived the place to be more dangerous. This was music to Monderman’s ears. If they had not felt less secure, he said, he “would have changed it immediately.” Emphasis mine.
When thinking about human behavior, it makes sense to understand what people perceive, which may be different from how things are, and will almost certainly be very different from how a removed third party thinks them to be. Traffic accidents are predominantly caused by people being inattentive. Increase the feeling of risk, and you increase the attention. I know when I am in traffic on my bike, I'm hyper-vigilant, and this has made me a better car driver.

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