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Highway Functional Classification: Concepts, Criteria and Procedures

Our nation’s roadway system is a vast network that connects places and people within and across national borders. Planners and engineers have developed elements of this network with particular travel objectives in mind. These objectives range from serving long-distance passenger and freight needs to serving neighborhood travel from residential developments to nearby shopping centers. The functional classification of roadways defines the role each element of the roadway network plays in serving these travel needs. Ultimately, the coordinated and systematic maintenance of an accurate roadway functional classification system ensures that Federal Aid funds are allocated where they are most needed, to enable people and goods move fluidly through our modern transportation system.

The Highway Functional Classification: Concepts, Criteria and Procedures, 2013 Edition, describes the procedures and processes for assigning functional classifications to roadways and adjusting urban area boundaries. This document builds upon and modifies prior guidance documents.

Why develop new guidance?

  • The Federal Aid system is mature. Modern functional classification processes typically involve reclassification of existing roads rather than the development of new networks in need of classification.
  • Classification of roadways is more comprehensive than before. Where vehicular mobility was the driver of historical classification needs, today’s classification process involves context, multimodal accommodation, and cross disciplinary consensus building between engineers, planners and communities.
  • Technology has changed. New methods for cataloging and tracking roadways such as Geographic Information Systems (GIS) enable precise spatial location of roadways as well as detailed mapping of highway systems.
  • Functional classification coding at the Federal level has been simplified. All functional classification categories will now exist in both urban and rural areas.
  • Urban Boundary delineation correlates with changes to urban area designation by the US Census Bureau. Guidance to coincide with the latest Census and FHWA requirements for urban areas was needed.

What is included in the updated guidance document?

  • Definitions and criteria for each highway classification category
  • Guidance, best practices and procedural tasks for functional classification maintenance
  • Discussion of the applications for Functional Classification including performance and design
  • Description of emerging and future classification trends
  • Definitions of urban area designations
  • Delineation of the technical tasks and considerations of adjusting urban area boundaries
  • Data transmittal requirements for urban area boundary adjustments