The Only Hope for Reducing Traffic

In 1962, transportation researcher Anthony Downs suggested that U.S. cities suffered from a fundamental law of highway congestion: "This Law states that on urban commuter expressways, peak-hour traffic congestion rises to meet maximum capacity." What was the case half a century ago remains true today. Except worse. In a research paper published in this month's American Economic Review, a pair of economists from the University of Toronto confirm the fundamental law of highway congestion, but argue it doesn't go far enough. By analyzing traffic data and road capacity in U.S. cities from 1983 to 2003, they also provide evidence for a fundamental law of road congestion — one that extends beyond interstate highways to include a "broad class of major urban roads."

In other words, no matter how many lanes of road you build in and around American cities, you can't stop cars from jamming them up. Despite the claims of highway advocates like the American Road and Transportation Builders Association, urban congestion can't be addressed by increasing road capacity. That's always been a tough fact for people to accept; as Lewis Mumford wrote back in the New Yorker back 1955: “People, it seems, find it hard to believe that the cure for congestion is not more facilities for congestion."