3.2 Functional Classification System

One of the initial steps in the design process is to define the function that the facility is to serve. The two major considerations in functionally classifying a roadway are access and mobility. Access and mobility are inversely related - that is, as access is increased, mobility is decreased. Roadways are functionally classified first and then contextually classified. The functional classification of roadways can be viewed on the

Statewide Planning Map

that is maintained by TxDOT's Transportation Planning and Programming Division (TPP) and is also shown in TxDOTConnect. The

Statewide Planning Map

, however, makes the appropriate distinction that freeways are in fact principal arterials. For purposes of design, freeways have unique geometric criteria that demand a separate design designation apart from other arterials. Key characteristics of each roadway type are defined in

Table 3-1

Figure 3-2

illustrates the hierarchy of roadways within the functional classification system.

Table 3-1: Roadway Functional Classification System
Functional Classification	Network Importance	Characteristics
Interstates / Freeways Expressways	Corridors of national importance providing long-distance travel	Limited Access Through traffic movements Long-distance traffic movements distance traffic movements Primary freight routes Possible transit network support No pedestrian or bicycle traffic Guided primarily by FHWA design standards
Principal Arterial	Corridors of regional importance connecting large activity centers¹	Non-access controlled Through traffic movements Long distance traffic movements Primary freight routes Some segments may include pedestrian and bicycle movements.
Minor Arterial	Corridors of local importance connecting activity centers¹	Connections between local areas and network principal arterial roadways Connections for through traffic between arterial roadways Access to public transit and through movements Pedestrian and bicycle movements
Major Collector	Roadways providing connections between arterials to local roads and streets	Traffic with trips ending in a specific area Access to commercial and residential centers Access to public transportation Pedestrian and bicycle movements
Minor Collector	Roadways providing connections between major collectors to local roads and streets	Fewer lanes, lower ADTs and more access points than major collectors Access to public transportation Pedestrian and bicycle movements
Local	All other roads	Direct property access – residential and commercial Pedestrian and bicycle movements
Notes:
An activity center is a concentrated area with a high density of diverse land uses and activities that generate significant traffic. These areas often include a mixture of commercial, recreational, institutional, entertainment, and tourism facilities. Examples include transit stations, shopping malls, park-and-ride facilities, business districts, and University campuses.

Functional Classification System and Hierarchy ( click in image to see full-size image)

Figure 3-2: Functional Classification System and Hierarchy

Source: FHWA Highway Functional Classification Concepts, Criteria and Procedures 2023 Edition

Chapter 3: Context and Facility Type Considerations