Important Highways for Intercity Travel - Possible Additions to the Interstate System After 1972

Highway planning is a process wherein a highway network con­ sidered adequate to meet both the present and future traffic demands of an auto-oriented, ever-growing populace is visualized. It is also the process in which a procedure designed to implement the plan should be formulated. The first step in the planning process is the determination of high­ way needs. The elimination of these needs results in structurally sound, safe system of highways. Such highway systems must be capable of handling large volumes of traffic efficiently, if this is to be their func­ tion, or of providing adequate access to the land, if that is to be their function. The technique by which each highway segment is placed in one of the several highway systems is known as highway classification. Most often, classification is accomplished by considering the relative degree to which a highway segment performs the two services of traffic movement and land access. A highway providing primarily for traffic movement must be characterized by high geometric design standards, an example of which is the Interstate System. Those highways provid­ ing primarily land access service may have caomparatively lower design standards. The purpose of this paper is to describe a planning tool which may be utilized in the classification of highways and, more specifically, an application of the tool in the selection of important highways in Indiana. These important highways, or at least traffic corridors, were deemed, by virtue of their anticipated traffic volumes, worthy of consideration for construction to high design standards. They supplement the Interstate System in the handling of large volumes of high speed traffic.