[konspence]

I had not heard of the Downs-Thomson Paradox, thank you very much for sharing it.

After reading the article I have to point out, from the "Restrictions on validity" section, that it "only applies to regions in which the vast majority of peak-hour commuting is done on rapid transit systems with separate rights of way".

So for most cities outside of NYC, this paradox supposedly does not apply (even though I feel it has some bearing).

Regardless, the general principle behind the paradox is induced demand (http://en.wikipedia.org/wiki/Induced_demand) - which, regardless of the share of transit users, will always apply to highway projects.