If a stretch of highway is often congested, we should add another lane to increase capacity. Wrong.
In “The Fundamental Law of Road Congestion: Evidence from U.S. Cities,” researchers show any increased capacity from additional roads is temporary. Traffic increases to fill the added capacity. The study’s startling findings include:
o The number of vehicle-kilometers traveled increases in proportion to the available lane-kilometers of roadways. If there are more roads, additional....