[vitoreiji]

> Ultimately the reason why adding more roads to a system produces more traffic is more people take cars vs. public transit.

More precisely, more people take cars vs. not take cars. "Not take cars" can be public transit, human powered transport or even not moving at all.

[mturmon]

This correction might seem pedantic, but I think it is important. One of the lessons of these "paradoxes" (more roads = more congestion) is that one must take into account the whole traffic system.

I'd add that another salient factor is people's housing choices relative to jobs and other destinations -- there is an interplay between road-building and housing construction.