Jarrett Walker at Human Transit has one of those bookmark posts that he seems to generate about once a month — this time about why transit and road capacity don’t solve congestion, and what remedies actually will.
Congestion reduction is a common slogan in any transportation infrastructure campaign. Like many slogans, it suffers from some definitional vagueness. Of course, in an obvious and minimal way a person who switches from driving to transit, or adding more road space to fit cars, reduces short-term congestion in some sense. In the long term, either way the free car capacity is consumed by induced demand.
What’s frustrating about capital project debates is that the general public hasn’t generally been sufficiently exposed to the concept of induced demand. On one level in the media, the debate is how much a capital project will or will not reduce congestion. Meanwhile, a wonkier debate using other metrics is going on places like this one. Project advocates are stuck with a very unattractive dilemma: essentially mislead the public (“we’ll reduce congestion!”) or try to educate people that nothing will, thus running the risk of sensationalist headlines (“project supporters admit measure won’t solve congestion.”)
Not only does Walker tackle this subject, but he ties into a cogent summary of why transit service is important (see my thoughts on this). Notably, the most clearly palatable solution to congestion, pricing, is one of the stronger reasons to support quality transit service. It’s an excellent piece and you should go read the whole thing.