Within a fairly short period of time, traffic congestion has eclipsed virtually every other concern -- be it crime, unemployment, or air pol lution -- as America's number one urban problem. Public opinion polls in San Francisco, Atlanta, Phoenix, Washington, D.C., and at least a dozen other urbanized areas show citizens are more fed up with con gestion than with anything else. In the Bay Area, congestion has been pegged by areawide residents as the number one public menace for four years straight, outdistancing its closest rival -- air pollution -- by more than two-to-one.