The effect of Phase I on congestion Congestion occurs when highway capacity is scarce. Supply and demand, the economist s traditional tools for evaluating the allocation of scarce resources, clarify the congestion problem.
Population growth increases the demand for automobile transportation.
Population in the central Puget Sound region grew by 82 percent from 1960 to 1990 and is expected to grow a further 50 percent from 1990 to 2020. Other factors combine to increase further the demand for automobile transportation. People choose where to live in order to be close to family and friends, to have access to good schools, and to be near to recreational resources. As a result, many locate a fair distance from their workplaces. Low cost suburban land has made it possible for families to live in low density neighborhoods and for employers to locate in low density work sites.