Walkable City by Jeff Speck

Author:Jeff Speck
Language: eng
Format: epub, mobi
Publisher: Farrar, Straus and Giroux

KEEP IT COMPLICATED

Narrower lanes are not the only way to slow traffic down. Each and every aspect of the built environment sends its own cue to drivers and too many of those cues say “speed up.” Most of them, unfortunately, are the law. Two more that deserve our attention are intersection geometry and sight triangles.

Recently, my wife and I took a road trip to Philadelphia. It was our first weekend alone without the two kids, and we were determined to make it count. The first stop, about a mile south of the Liberty Bell, was the intersection of Ninth Street and Passyunk Avenue. Fast-food aficionados will recognize this address as the location of Geno’s Steaks and Pat’s King of Steaks, the two oversized food stands that have been duking it out for decades over the title of Best Philly Cheesesteak.

I had heard about the cheesesteak duel, but I was not aware of the odd urban condition that surrounds it. As befits their embattled circumstances, the two restaurants sit nose-to-nose on opposing flatiron lots, like two skinny slices of pie, framed by two streets that cross in a sharp thirty-degree X. Pat’s points north, directly at Geno’s pointing south. With all their flashy signage, they look like two casino yachts playing a game of chicken.

For me, the question wasn’t which sandwich was better (my vote goes to Pat’s●). Rather, the question was: After all the cheesesteaks these two establishments had undoubtedly served to traffic engineers throughout the years, why is it still illegal in most of America to intersect two streets at a thirty-degree angle?

Observing the intersection at work, it would be hard to imagine a safer scene. First, there were the snaking lines of customers that made their way right into the street. We planners call this “human traffic calming”—as opposed to “human speed bumps,” another common phenomenon—and the traffic was further slowed by all the cars pulling in for curbside pickups. But even without this confusion—we returned when the crowds had abated—the simple fact was that nobody drove dangerously through this intersection, precisely because the intersection felt dangerous.

Welcome to the world of risk homeostasis, a very real place that exists well outside the blinkered gaze of the traffic engineering profession. Risk homeostasis describes how people automatically adjust their behavior to maintain a comfortable level of risk. It explains why poisoning deaths went up after childproof caps were introduced—people stopped hiding their medicines—and why the deadliest intersections in America are typically the ones you can navigate with one finger on the steering wheel and a cellphone at your ear.9

The best risk-homeostasis story comes from Sweden, a nation that is obsessed with traffic safety. If you look at the bar chart of Swedish traffic fatalities through the years, most of what you see is not surprising. There is the rise in deaths into the sixties, the decline as seatbelts are introduced, the leveling off in the eighties, and then a further decline as airbags become standard equipment. But, wait a minute,

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