Responding to Congestion and Traffic Growth: Transportatoin Demand Management

American attitudes toward transportation planning have undergone significant change. For three decades after World War II, public policy emphasized construction of new highway and transit facilities to remove the backlog of needs resulting from the combined effects of depression, a war economy, and postwar economic expansion, suburbanization, and accelerating automobile ownership. There was consensus among transportation policy makers that their primary goal was to accommodate growth by constructing facilities which would have adequate capacity to handle future demand. There was also consensus that providing adequate capacity to handle future demand. There was also consensus that providing adequate capacity was an achievable goal. It was understood that land use patterns and economic development were the sources of traffic, yet there was general agreement that transportation policy should aim to accommodate rather than regulate or control land use and economic growth. In the decade of the 1980's the policy goal of accommodating traffic demand appeared less and less viable. Continued (and in some areas explosive) urban growth and automobile use without any corresponding increase in highway transportation facilities has led to unprecedented levels of traffic congestion in many metropolitan areas (Hanks and Lomax, 1991). Rising traffic congestion has as a result become a major public policy issue and a primary target for anti-growth activists.