Transportation system is the future development of metropolitan areas : the permanent corridor concept.

This paper develops a concept of permanent transportation corridors and network configuration that allow for long-range planning. It indicates that an optimum network of major transportation facilities, initially spaced at 4 to 6 miles and eventually spaced at 2 to3 miles in built-up areas, can function into the future at reasonable levels of service for any predicted rates of population growth, urban area expansion, and increased travel demand.