Wednesday, December 1, 2010

Another Link

It seems that when I bring up a point, I find some bit to back it up. This time around, it is about the traffic engineer. In a previous post, I linked a story about how the Florida DOT won't make an urban street with a State Highway designation urban friendly in Miami.

This link comes from a former traffic engineer. I find myself taking this at face value (I have no idea who the guy is and if is is truly a traffic engineer). But it does make the same points I did, with a couple exceptions.

The first, they are doing what they are doing in their version of safety, primarily car users. Though, it would appear the author came to a revelation that planners have argued for a while. The "safer" streets generally have more accidents.

This has everything to do with the anomaly of human behavior. We tend to slow down, look more and overall drive better when we feel unsafe. Real world example happens here in downtown all the time. You can tell a visitor from a worker by how they drive. Visitors tend to be slower and looking around more while those that drive here frequently go faster, text or run lights.

Which leads to the second, that math-based applications for human behavior is prone to failure. On a very general level, math is useful. Modelling traffic patterns is no more than several mathematical equations based over a geography divided into zones. Still, in every region, the model has to be calibrated, meaning the original equations do not fit well and have to be modified to fit real world observations.

Yet, traffic engineers will float these formulas out there as if it is physics and say we need X across all spectrum's. This is bad for our streets and bad for our urban cities. What's good for suburban Long Island isn't for downtown Dallas. What works for Arlington, doesn't for Oakland. Yet, for decades now, traffic engineers have used these math formulas, usually derived from regression analysis and applied them unilaterally across the board.

Ironically, there are places that are taking spaces for cars only and making them for everybody. New York, San Francisco, Milwaukee and Portland have all taken highways or major routes away from cars and usually turned them into "complete streets" or pedestrian ways. Each time, traffic engineers warned of increased congestion and traffic nightmares. Each time, that proved to be false. Apparently, they have no mathematical formula for decreased space. But, if they were to use a standard linear regression analysis, they'd have to observe it in the real world, which is precisely what they work towards not seeing happen. What little has actually happened, is so small that the statistical margin of error would make the formula irrelevant

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