Introduction to Rural Functional Class Maps

The current electronic and printed versions of the Rural Functional Class Maps shall supercede all previous editions.

These maps depict the approved revisions to the 1993 National Functional Classification System of rural areas. Both the national system and the revisions to it have been approved by the Federal Highway Administration (FHWA).

Functional classification has been an important factor in Federal-aid highway programs for many decades. A roadway functional classification system has been helpful to a variety of government agencies in areas of planning, organizing, jurisdictional responsibility and cost allocation.

Functional classification is the process by which streets and highways are grouped into classes according to the character of service they are intended to provide. Cities, towns, businesses, farms, homes, schools, recreation areas and other places generate or attract trips. These trips involves movement of vehicles through a network of roads. It becomes necessary to determine how travel movement can be channelized within a limited road network in a logical and efficient manner. Functional classification defines the nature of this channelization process by defining the role that any particular road or street should play in serving the flow of trips through a road network. The heavy travel movements are directly served by major channels, and the lesser trips are channeled into somewhat indirect paths.

The Functional Classification System is divided into rural and urban areas. The characteristics of these two areas are different in the types of land use, street and highway networks and the nature of travel patterns. The classification data for rural area roadways is known as The County Collector System. For a more detail description of the urban functional classification system, see the State’s Urban Area Functional Classification section.

Rural roads consist of those facilities that are outside of small urban and urbanized areas. They are classified into the following four major systems:

Rural Principal Arterial System

The rural principal arterial system consists of a connected rural network of continuous routes having the following characteristics:

1. Highways having high density of intrastate and interstate travel.
2. Highways that serve urbanized areas and a large majority of small urban areas. The rural principal arterial system may serve an urban area if the system either penetrates the urban boundary or comes within 10 miles.
3. Provide an integrated network without stub connections except where unusual geographic or traffic flow conditions dictate otherwise.

The principal arterial system is classified into the following two subsystems:

1. Interstate System: All designated Interstate routes.
2. Other Principal Arterials: All non-Interstate principal arterial highways.

Rural Minor Arterial System

The rural minor arterial system should in conjunction with the principal arterial system, form a rural network having the following characteristics:

1. Link cities and larger towns and other traffic generators, such as major resort areas, that are capable of attracting travel over similarly long distances and form an integrated network providing interstate and intercounty service. Minor arterial system serves an urban area if the system either penetrates or comes within 2 miles of the urban boundary.
2. Be spaced at such intervals, consistent with population density, so that all developed areas of the State are within a reasonable distance of an arterial highway.
3. Provide service to roads with trip length and travel density greater than those predominantly served by rural collectors or local systems. Minor arterial routes have relatively high overall travel speeds and minimum interference to through traffic.

Rural Collector System

The rural collector routes generally serve travel of primarily intracounty rather than statewide importance and constitute those routes on which (regardless of traffic volume) predominant travel distances are shorter than on arterial routes. More moderate speeds will be typical.

The characteristics of rural collector system is subclassified according to the following criteria:

Major Collector Highways and Roads:

1. Provide service to any county seat not on an arterial route; to the larger towns not directly served by the higher systems; and to other traffic generators of equivalent intracounty importance, such as consolidated schools, shipping points, county parks, important mining and agricultural areas, etc.
2. Link these places with nearby larger towns or cities or with routes of higher classification.
3. Serves the more important intracounty travel.

Minor Collector Roads:

1. Be spaced at intervals, consistent with population density, to collect traffic from local roads and bring all developed areas within a reasonable distance of a collector road.
2. Provides service to the remaining smaller communities.

Rural Local Roads System

The rural local roads system should have the following characteristics:

1. Serves primarily to provide access to adjacent land.
2. Provides service to travel over relatively short distances as compared to collectors or other higher systems. Local roads will, of course, constitute the rural mileage not classified as part of the principal arteial, minor arterial, or collector systems.