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Roadway Functional Classification

"Functional classification is the process by which streets and highways are grouped into classes, or systems, according to the character of service they are intended to provide. Basic to this process is the recognition that individual roads and streets do not serve travel independently in any major way. Rather, most travel involves movement through a network of roads. It becomes necessary then to determine how this travel can be channelized within the network in a logical and efficient manner. Functional classification defines the nature of this channelization process by defining the part that any particular road or street should play in serving the flow of trips through a highway network."  (FHWA, 1989)

Road Functional Classes in Your Community

Roadway functional class can be used at the local government level to provide a direct link between transportation and land use.  Local comprehensive plans should consider the interaction between adjacent land use and transportation facilities by establishing policies that link access to property, zoning, and development density to the functional classification of area roadways.  A well-defined functional classification system in combination with designated truck routes can also be used to direct freight movements to appropriate facilities.

IDOT has developed an interactive map showing functional class designations regionwide to make it easier for residents to determine the designations of roads in their communities.  In addition, key route type and key route numbers of roadways can be looked up for use on IDOT applications (instructions). This information was drawn from the Illinois Roadway Information System, and is refreshed nightly to reflect current information.   In addition, IDOT publishes 5-Year Functional Class Township Maps in .pdf format.   District 1 includes the maps for northeastern Illinois.  You may look up your township name on the northeastern Illinois township map.

Changing Functional Class Designations

Over time, as development in an area changes, the function served by a roadway can change.  CMAP developed a workbook to help communities navigate the process. 

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