There is no question that congestion is a serious problem in this country -- and a crippling problem in some cities. Nor is there any question that congestion is much worse than it was ten years ago, even if high gas prices and the recession have caused it to level off in some places.
But the Texas Transportation Institute is guilty of a bit of hyperbole when it announces that "[t]he overall cost [of congestion](based on wasted fuel and lost productivity) reached $87.2 billion in 2007 – more than $750 for every U.S. traveler."
TTI uses free-flow traffic as its baseline for measuring congestion. In particular, it defines "Delay per Peak Traveler" to be "[t]he extra time spent traveling at congested speeds rather than free-flow speeds divided by the number of persons making a trip during the peak period." (Summary report p.1)
Honestly, free-flow speed is not the right baseline. There is no realistic, hypothetical state of the world in which we would experience perfect, free-flow traffic everywhere. It would not be feasible to build enough roads (or charge enough for them), particularly since free-flow speeds would entice more drivers onto the road. So to imply that there is $87 billion of waste to be saved -- and I think TTI does imply this -- is simply wrong. The TTI report makes the news every year thanks to this spectacular estimate, but this one probably belongs on the tabloid pages.
Anthony Downs makes this point in Still Stuck in Traffic, pp. 23-24 (available on-line at Google Books). He makes several other reasonable criticisms of TTI's methodology. Hedoes recognize that TTI's methodology and findings are useful, and he does not dispute (nor do I) that congestion is a serious problem that we can't simply build our way out of.
(Edited and cross-posted from Urban Returns.)
