The study considered systems of several sizes, testing each by a variety of criteria, and recommended as optimum a rural network of 33,900 miles. The need for an additional 5,000 miles of auxiliary urban routes was foreseen, bringing the total proposed system to about 39,000 miles, of which one-fifth would be in urban areas.
High standards of geometric design with full control of access were recommended. No overall cost estimate for the system was made. It was suggested that postwar expenditures for its construction should be $750 million a year, two-thirds of it on the urban sections.
Designation of the System
Acting on the basis of the 1939 and 1944 reports, the Congress in the Federal-Aid Highway Act of 1944 directed the designation of a National System of Interstate Highways limited to 40,000 miles and “. . . so located as to connect by routes, as direct as practicable, the principal metropolitan areas, cities, and industrial centers, to serve the national defense, and to connect at suitable border points with routes of continental importance . . .”
The Act provided that the routes of the National System of Interstate Highways be selected by joint action of the State highway department of each State and the adjoining States, with the approval of the Public Roads Administration and were to be incorporated in the Federal-Aid Primary System if not already included in it.
In response to a request from PRA, the States proposed routes for inclusion in the System. Criteria for selection included service to cities and rural population, to manufacturing and agricultural production, to concentrations of motor-vehicle ownership and traffic, and to national defense. Additional criteria in urban areas included consideration of need for through and circumferential routes and their relation to land use, urban planning, and civil defense.
Considerable discussion ensued between the States and the Department of Defense. On August 2, 1947, selection of the general locations of the main routes of the Interstate System was announced. They totaled 37,700 miles, including 2,900 in urban areas. The remaining mileage within the 40,000-mile limit was reserved for auxiliary urban routes.
Again on the recommendation of and in consultation with the States and the Department of Defense, the general locations of 2,300 miles of urban circumferential and distributing routes were designated on September 15, 1955.
This well designed interchange in Morris County, N.J., maintains much of the original topography while smoothly blending the heavy traffic of I-80 and 287 with that of U.S. 46. It provides long acceleration and deceleration lanes and wide shoulders for safe emergency stops.
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