§ 2.4. Transportation Planning Concepts

2.4.1 Urban, Transitioning and Rural Areas

Many Federal transportation programs and policies rely upon a clear and well-documented distinction between urban and rural areas. Urban and rural areas are explicitly defined by the Census Bureau according to specific population, density and related criteria. From these technical definitions, irregularities and boundaries that are separated from or inconsistent with transportation features may result. For transportation purposes, States have the option of using census-defined urban boundaries exclusively, or they may adjust the census-defined boundaries to be more consistent with transportation needs. In general, there are also differences in the way FHWA and the Census Bureau define and describe urban and rural areas. The Census Bureau defines urban areas solely for the purpose of tabulating and presenting Census Bureau statistical data. According to 23 U.S.C. 101(a)(33), areas of population greater than 5,000 can qualify as urban, in contrast to the Census Bureau's threshold of 2,500. There are also differences in the terminology used to describe sub-categories of urban areas. FHWA refers to the smallest urban area as a Small Urban Area, while the Census Bureau refers to Urban Clusters. FHWYs definitions are summarized in Table 2-1 below.

Table 2-1: FHWA Area Definitions

	Population Range	Allowed Urban Area Boundary Adjustments
Urban Area	5,000+	Yes
Small Urban Area (From Clusters)	5,000-49,999	Yes
Urbanized Area	50,000+	Yes

 

Map 2-1 depicts the functional classifications for Santa Rosa County roadways and the FHWA designated areas used in determining these functional classifications.

2.4.1.1. Urbanized Area

The urbanized area is an important factor in determining the functional classification of a roadway, as well as determining the area within the County to be part of the planning area of the Transportation Planning Organization. The Urbanized Area Boundary is an area that consists of a densely settled core of census tracts and census blocks that meet minimum population density requirements, along with adjacent densely settled surrounding census blocks that together encompass a population of at least 50,000 people. These areas are initially established by the U.S. Bureau of Census with the decennial census and for transportation purposes adjusted slightly by the TPO, in consultation with FDOT and the Federal Highway Administration.

Any adjusted Census urban area boundary must be agreed on by the appropriate local governmental officials (City, County and/or MPO) in cooperation with the District Office and TranStat, and approved by Federal Highway Administration (FHWA). This final boundary is referred to as the FHWA urban or urbanized area boundary. FHWA adjusted urban area boundaries are to be established before or concurrent with initiating functional classification activities within a given county.

Census boundaries can and should be expanded so as to smooth out irregularities, maintain administrative continuity of peripheral routes, and encompass fringe areas having residential, commercial, industrial, and/or national defense significance. Transportation terminals serving the area such as airports and seaports should also be included within the redefined area if they lie within a reasonable distance of the urban area boundary that would otherwise be selected. Careful consideration should be given to the selection of boundary locations which will include logical control points for transportation linkages such as interchanges, major cross roads, etc., where the inclusion of such areas will not unduly distort the urban area as would otherwise be selected. Boundaries should not be modified to accommodate a single project.

2.4.1.2 Transitioning Area

Transitioning Areas are "fringe" areas that exhibit characteristics between rural and urban/urbanized characteristics. Transitioning Area boundaries are important for several aspects of transportation planning and facilities development and operations in Florida. Transitioning Area boundaries are used in the determination of Level of Service (LOS) standards and capacity/LOS measurement, access management, interchange spacing, signage, and posted speed limits, and they may be a factor in determining design standards for roadway improvements. As such, they have significant impact on corridor studies (including PD&E studies), project traffic analyses, local impact analyses, and overall design standards for roadway improvements.

2.4.1.3 Rural Area

The U.S. Department of Transportation defines rural in two ways: first, for highway functional classification and outdoor advertising regulations, rural is considered anything outside of an area with a population of 5,000; second, for planning purposes, rural is considered to be areas outside of metropolitan areas 50,000 or greater in population. This definition leaves a lot of room for significant differences within these categories. Therefore, it is prudent to describe rural based upon what we see across the country. For the purposes of this document, "rural" is considered to be non-metropolitan areas outside the limits of any incorporated or unincorporated city, town, or village.

Map 2-1 Federal Highways Administration Boundary & Functional Classification of Roads within Santa Rosa County, Florida

2.4.2 Functional Classification

Functional classification is defined in the Florida Department of Transportation's Urban Boundary and Functional Classification Handbook (2013). Functional classification is the process when streets and highways are grouped into classes, or systems, according to the character of service they provide. The designation of functional classification is made at least once every 10 years following the decennial Census.

According to FDOT's Handbook, travel desire relates to functional classification, with arterials representing the heaviest used trip route and locals representing the least used facility. The arterial system provides a high level of through traffic movement, local facilities provide predominantly direct property access and the collector system lies between the other two. Conceptually, in rural areas, arterial highways provide direct service between cities and larger towns and accommodate longer trip lengths. Collectors serve small towns and connect them to the arterial system. Local roads serve individual farms and other rural property uses ultimately tying to collectors. The same basic concepts apply in urban areas. The urban roadway network connects residential, commercial and public areas by this hierarchy of arterial, collector and local roads.

Five functional classification categories ( Table 2-2 ) are common to rural and urban roads. The rural or urban designation is part of the complete functional classification designation; e.g., Urban Minor Arterial.

Table 2-2: Functional Classification Hierarchy

Urban	Rural
Principal Arterial	Principal Arterial
Minor Arterial	Minor Arterial
Major Collector	Major Collector
Minor Collector	Minor Collector
Local	Local