For a quarter century, a top priority in transportation economic theory has been to develop models of rush-hour traffic dynamics that incorporate traffic jams (hypercongestion). The difficulty has been that "proper" models result in mathematical intractabilty, while none of the proposed...

In 2000, the average driver in US metropolitan areas endured 27 hours of traffic delays, a rise from 7 hours in 1980. In many other countries, traffic delays are considerably worse than in the United States, and in developing countries urban traffic congestion is increasing with alarming...