MoDOT, Traffic On 64/40, and the Fundamental Law of Road Congestion

I have heard some complaints from people, via talk radio and message boards, that after two years and more than a half billion dollars, I-64/40 still has traffic jams at rush hour. I have news for the complainers: They could have expanded it to 10 lanes in each direction, and eventually it would still get backed up (I exaggerate, but only a bit). First, let’s all admit that we can’t properly judge the new highway’s traffic issues after only three rush hours, and this morning’s took place in poor weather. Beyond that, however, there is something called the Fundamental Law of Road Congestion. In short, as you expand capacity, which MoDOT did for part of the new project, you release latent demand that fills up that capacity.

Dr. Ken Small is one of the leading urban and transportation economists. He wrote a study for the Show-Me Institute that we thought was terrific. He’s also written extensively about road congestion. If the people of Missouri want reduced traffic jams, there is only one way to do it, and it isn’t capacity expansion. (Don’t take this as indicating a blanket opposition to capacity expansion. There are plenty of reasons that such expansion is often needed.) The only way to reduce congestion in Missouri is through pricing. If you want your roads to be “free,” you’ll get high traffic at peak times. On the other hand, if you want free-flowing traffic on highways at 5:30 p.m., the only way to do it is to charge a toll that continually adjusts pricing as demand changes.

MoDOT did an amazing job with the project, and so did the private contractors involved. But MoDOT does not control the laws of economics, and there is nothing they could have done to eliminate congestion.