The Fundamental Law of Road Congestion: Evidence from US cities
http://www.nber.org/papers/w15376

[...][These findings and others in the paper imply something broader than Down’s
law,  a law of road congestion that applies to highways and major urban roads in metropolitan
areas. In turn, this suggests that increased provision of highways and major urban roads is unlikely
to relieve congestion of these roads. ][...]