Turner explains his two traffic equations to NPR's weekend All Things Considered host Guy Raz:
[If you increase the number of highways in a city by 1 percent, it causes driving to also increase by 1 percent.]
[Increasing public transit by 1 percent has no effect on traffic.] However, it will have a positive impact on public transit.
"Ultimately, Turner's research has shown that the only way to deal with congestion is to follow the lead of cities like London, Singapore and Stockholm, which have adopted "congestion pricing" - tolls on people driving in the center city. Turner says Stockholm, specifically, has seen a 50 percent reduction in travel time at peak times because of tolls."
Turner's 4 July 2010 draft paper, "The Fundamental Law of Road Congestion: Evidence from US cities" is available from the NPR webpage.
Thanks to Eric Gilbertson