SUMMARY AND RECOMMENDATIONS
THE NATIONAL SYSTEM OF INTERSTATE HIGHWAYS
The National System of Interstate Highways is the trunk-line highway system of the United States. It connects all the largest cities and most of the larger ones. On its rural sections it serves 20 percent of the traffic carried by all rural roads. Its urban sections thus far designated, to which further designation will add an almost equal mileage, now serves more than 10 percent of the traffic moving over all city streets.
This large measure of service is rendered by a network that includes only 1 percent of the country’s total mileage of roads and streets. Without doubt, this system forms the most important connected network within the highway system of the country for service of the economy of peace.
Strategic importance of the interstate system
The National Military Establishment has determined that this same system includes in its rural sections substantially the roads of greatest strategic importance for service of the highway necessities of war. The urban sections designated are rated with the same authority as of prime importance for wartime duty, and the additional urban designation desirable for service of wartime movements is identical in character with the additional needs of normal usage in peace. This additional designation, consisting largely of circumferential routes in and around the larger cities, should be completed as promptly as possible.
A substantial part of the street network of our cities and much of the rural road mileage improved during a period of 40 years past, is seriously obsolescent. Traffic has grown faster than the responsive improvement of the street and highway facilities. Of the entire street and highway network, the interstate highway system, its most important segment, is by and large the most seriously obsolescent part. In the general lifting of arterial highway standards that is now needed and overlong delayed, the routes comprising the interstate system should be among the first considered for improvement.
Condition of the system
Recent research and development have provided definite guides which determine in detail the standards of design required for the adequate service of traffic of specific volumes and classes. The proper application of these standards will not only assure a safe and efficient accommodation of present traffic; it will also provide for the expected greater traffic of the future a facility of continuing usefulness, if the size and weight of vehicles are held within the limits recommended.
The determined conditions of the interstate system have been weighed against these standards, and the system has been found seriously deficient. It is most deficient in its sight distances and in the width of its pavements, shoulders, and bridges. The sight-
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