Periods covered
The estimates presented in this report cover two periods:
First 10 years, 1955–64.—Estimates were prepared to provide that each road system will be improved, by the end of 1964, to a condition adequate for its predicted traffic in 1964 (1974 in the case of the interstate system).
Next 20 years, 1965–84.—On the assumption that adequacy will be reached in 1964, estimates were prepared to provide for sustaining adequacy thereafter. The States supplied these estimates for the 20 years, 1965–84.
SYSTEM IMPROVEMENT
One of the principal objectives of the needs study was to develop costs that are realistic estimates of needs, unaffected by preconceptions of ability to finance or execute a peers. The proposed development of the various road systems is described briefly in the following paragraphs.
Interstate system
1955–64.—During the first 10 years the concept of development for the interstate system contemplates improvement of the entire system so that by the end of the period every road section will be structurally adequate, will have lane width sufficient to carry traffic predicted for 1974, and will otherwise be adequate for 30 to 40 years from the date of its construction.
1965–84.—The system is to be kept in continuing sound structural and functional condition after 1964. After 1974 additional lanes will be built as traffic needs warrant.
Other Federal-aid primary
1955–64.—The concept of development for the Federal-aid primary system (exclusive of the interstate system) for the first 10 years is to provide improvements so that the system will, by the end of 1964, be adequate for traffic of that year. y road section improved during this period shall have a generally high-type surface, a sufficient number of lanes to take care of traffic for 10 years, and adequacy in other geometric respects for 30 years from the date of its construction.
1965–84.—As road sections become inadequate structurally or functionally, after 1964, they shall be rebuilt in accordance with a continuation of the concept for the first 10 years.
All other systems
1955–64.—For the more a important and heavily traveled roads and streets of all other systems, the 1955–64 improvement contemplated is similar to that for the “other Federal-aid primary,” except that shorter service lives and lower type surfaces may be used. For the less important and lightly traveled roads and streets, the need is generally one of providing locally acceptable traffic service.
1965–84.—After 1964, all roads and streets shall be kept adequate in accordance with continuation of the concept for the first 10 years.
Design standards
When a road or street is to be improved, the new construction should conform to certain requirements for width, alinement, grade, and so on. These requirements are called geometric design standards,
