Despite an essentially static population, the number of vehicles in the city grew by an average of .5 percent every year between 1982 and 1993 (the last years for which statistics are available). Actual vehicle miles traveled - the stuff of which hair-tearing congestion and delays are made - rose almost 1.4 percent yearly in the late 80s and early 90s.

Neither of those figures is enough to make anyone's jaw drop. Their power is instead that of a single drop of water: Individually harmless, but torture in their cumulative effect. Even though fully 40 percent of Philadelphia's population doesn't own a car, even though we have an excellent mass-transit infrastructure, demand on the roads within the City limits continues to grow.

If traffic congestion were simply a matter of personal inconvenience, perhaps we might all agree that it's a terrible thing and make do. Unfortunately, to see Philadelphia's traffic problems in that light is to ignore some central economic and environmental facts.