How to Reduce Congestion: Build More Roads?

Where would you go for serious analysis of a subject like road congestion? A blog dedicated to such matters? Of course. The home pages of university professors who write on the subject? Naturally. Amazon.com? Um, yes, it turns out. I received an email from one Peter Schaeffer today, pointing me to the Amazon page for a book entitled "The Road More Traveled: Why the Congestion Crisis Matters More Than You Think, and What We Can Do About It".

The thing to do is to scroll down and read the two reviews, by Eric Wigginton of Jersey City and Rob Shearer of Mt. Juliet. Both of them do an excellent job of summarizing the book's main arguments, and especially the argument that the single best thing one can do to reduce congestion is to build more roads.

Now, I'm a Londoner, and having seen what happened when the UK government built the M25 motorway, I'm going to take a bit of convincing on this front. On the other hand, it's does seem to be true that cities with low pavement-to-population ratios, like Los Angeles, have worse congestion than cities with high pavement-to-population ratios, like Houston. Indeed, we're told that Houston is a prime example of a city which "built its way out of congestion".

Schaeffer was responding to an old blog post of mine, in which I said, essentially, that traffic expands to fill the roads available. I still think that's true – up to a point. Eventually, if land is very cheap (as it is in Texas), it might be possible to build so many roads that everybody can drive around in a car to their heart's content without causing any congestion. But I'm not sure that most cities want to end up like Houston, which I've visited a couple of times and which strikes me as one big parking lot.

It's certainly important to reduce congestion. But the reason people are keen on doing so through mass transit rather than road building is not (or not only) because mass transit is a more effective solution to the congestion problem. The other big reason is that mass transit allows much higher population densities, and a city with a high population density will be more vibrant, more economically productive, and more environmentally friendly.