Definitions: Federal-aid Highways, Federal-aid Systems and Federal-aid Eligible

Here are the Title 23 USC, FHWA and MDOT definitions related to the Functional Classification statewide review.

National Functional Classification (NFC) - NFC is a MDOT term for the Highway Functional Classification values. FHWA developed the Highway Functional Classification method for all public roads. The higher functions emphasize mobility, the lower functions have more property access. The values from the highest mobility function down to the lowest include: Interstate, Other Freeways, Other Principal Arterials, Minor Arterials, Major Collectors, Minor Collectors and Local.

Adjusted Census Urban Boundary (ACUB) - At MDOT, it is the resulting area from adjusting the U.S. Census decennial urban areas over 5,000 populations outward in a cooperative process by transportation agencies following federal guidelines. The roads, cities and villages within or on the ACUB border are urban, the roads, cities and villages outside the ACUB are rural.

Federal-Aid Highways - Defined in Title 23 CFR 470.101(5) defines the term "federal-aid highways" as public roads "other than a highway classified as a local road or rural minor collector." 

Federal-Aid Highway Systems - Defined in Title 23 CFR 470.103 to mean "the NHS and the Dwight D. Eisenhower National System of Interstate and Defense Highways (the "Interstate System")". In effect, 'federal-aid highway systems' is another name for the NHS.

Federal-Aid Eligible - At MDOT, it is a term for a road that is fully eligible for federal Surface Transportation Program (STP) road funds. The roads that are federal-aid eligible are federal-aid highways. This eligibility is determined by a combination of the roads NFC, urban/rural designation, and current federal transportation legislation, Fixing America's Surface Transportation Act (FAST-Act).

Limited Federal-Aid Eligible - Rural minor collectors have limited eligibility for STP funds.

Federal-Aid or Federal-Aid Systems - These terms are not legally defined. At MDOT, they are used to include all roads that have some type of eligibility to federal funds, these include the federal-aid highways, limited federal-aid eligible rural minor collectors and the NHS routes.

Federal-Aid Eligible Highway Systems - Language used in Act 499 for the Transportation Asset Management Council (TAMC), routes included in this are open to interpretation by the council.

National Highway System (NHS) - FHWA states the NHS consists of roadways important to the nation's economy, defense, and mobility.The National Highway System (NHS) includes the following subsystems of roadways (note that a specific highway route may be on more than one subsystem):

  • Interstate: The Eisenhower Interstate System of highways retains its separate identity within the NHS.
  • Other Principal Arterials: These are highways in rural and urban areas which provide access between an arterial and a major port, airport, public transportation facility, or other intermodal transportation facility.
  • Strategic Highway Network (STRAHNET): This is a network of highways which are important to the United States' strategic defense policy and which provide defense access, continuity and emergency capabilities for defense purposes.
  • Major Strategic Highway Network Connectors: These are highways which provide access between major military installations and highways which are part of the Strategic Highway Network.
  • Intermodal Connectors: These highways provide access between major intermodal facilities and the other four subsystems making up the National Highway System.

The National Highway System (NHS) includes the Interstate Highway System as well as other roads important to the nation's economy, defense, and mobility. The NHS was developed by the Department of Transportation (DOT) in cooperation with the states, local officials, and metropolitan planning organizations (MPOs).

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