Friday, November 8th, 2013
Clark Williams-Derry, a blogger with the Sightline Institute, has been running a blog series called “Dude, Where Are My Cars?” which examines the increasing disconnect between traffic projections and traffic reality. The Sightline Institute is into sustainability advocacy, so would naturally have an anti-car POV, but there’s some interesting stuff in there. I was particularly struck by this graphic that’s been making the rounds:
In other words, the Washington DOT continues to use basically the same upward slope for future traffic predictions despite the fact that traffic has been on a steady downward slope since 1996. They just slide the origin point down the actual curve. Williams-Derry straightforwardly calls this “B.S.” He then proceeds to give a point by point rebuttal of the DOT’s claims regarding their projection.
He has strong words and in my experience they are somewhat justified. I try to give people the benefit of the doubt, but that’s becoming harder and harder to do in these cases. However, lest we be too harsh, keep in mind that transport is highly politicized, and staff bureaucrats, many of whom are no doubt not particularly well-paid, are under enormous pressure to toe the party line set by the political overlords. It’s not realistic to expect most of them to stick their necks out, particularly when there’s so little chance it would actually affect the outcome in any case. Like with Jay Carney, the job of a spokesman is to aggressively promote and defend the boss and his policies, not to go on some Socratic quest for the truth.
This also shows how incredibly difficult it can be refute DOT claims. Their traffic models are basically black boxes. As we all know, garbage in, garbage out. It’s very easy to tweak parameters in any model to get the results you want. Also, it’s not always obvious what the parameters in fact are. While some items like population and job growth can be fairly easily analyzed and critiqued, it’s usually hard to get a grip on much of the model. If they say the number in 2040 is X, how do you know if it’s too high or too low? Most of the time you don’t.
Thus the person who wants to try to understand if these are legitimate versus manufactured numbers has to read through reams of dry, technical material to accomplish one or both of two things (assuming there’s a problem): show inconsistency between numbers, or draw an easy to understand picture for the public of what the numbers actually imply if you believe them. One the latter point, much like some companies that disclose troubling information right in the prospectus on the assumption no one who happens to read it will notice or care, sometimes the dirt is right there for anyone who wants to read through some material. I’d put the recent Louisville bridge study into that category.
Unfortunately, few people have the time or inclination to do this. And with the state of newspapers as they are, there are very few transport reporters who are able to do a real analysis. This means that when you read the average article about transportation in the newspaper, it’s usually little more than a re-written DOT press release. Given that the papers will print whatever the DOT spokesman tells them uncritically, why not take advantage of that to the max? No surprise, that’s exactly what they do.