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FHWA Functional Classification Guidelines

Section I - Introduction

Note: This publication was updated in 2013. This version is for archival purposes. For the current version, see

Revised in 1989, this document was electronically scanned in April, 2000. The scanned image was processed through Optical Character Recognition software, the resulting text being formatted for the World Wide Web. Changes are restricted to:

This reference manual includes sections on (1) concepts of functional highway classification and functional system characteristics and (2) suggested procedures for functional highway classification in rural, small urban and urbanized areas. The material herein is adapted from two previous FHWA manuals concerned with functional highway classification. The relationship of this manual to these previous documents is discussed below.

Two nationwide studies of functional highway classification were conducted during the period 1969-1971. The first of these, using criteria and procedures specified in the 1968 National Highway Functional Classification Study Manual, called for the functional classification of existing (1968) highways. The second study was carried out in accordance with procedures specified in the National Highway- Functional Classification and Needs Study Manual (1970 to 1990) . This latter study used the same functional classes and basic functional criteria as the first study, but provided for the classification to be based on projected 1990 facilities and usage.

The Federal-Aid Highway Act of 1973 required the use of functional highway classification to update and modify the Federal-aid highway systems by July 1, 1976. This legislative requirement is still effective today. Also a number of States have adapted the functional classes and criteria from these studies for their own purposes. For both these reasons, a need has developed for a republication of the functional classification concepts and criteria that were expressed in the aforementioned manuals, without the reference to specific study requirements that pertained in those manuals.

The functional classes and their characteristics defined in this manual are, for the most part, identical to those in the predecessor manuals. Text has been reworded only to the extent necessary for consistency and clarity and to delete reference to the original studies. The discussion of functional classification concepts is taken intact from the earlier of the two manuals.

Also included herein is a discussion of suggested classification procedures for rural, small urban and urbanized areas, which derives from the predecessor manuals, relying largely, in fact, on their original wording. This approach therefore provides first, a description of suggested procedures for classifying an existing network, followed by procedural suggestions for developing an updated or "future year" classification.

Procedures for functional classification in urbanized areas should be developed within the framework of the continuing, comprehensive, and cooperative planning process carried out pursuant to Section 134 of Title 23, U.S. Code.

Updated: 1/31/2017
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