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Highway Functional Classification: Concepts, Criteria and Procedures

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TABLE OF CONTENTS

Section 1. Introduction ..................................................................................................... 1

1.1 Overview .........................................................................................................2

Section 2. Concepts ......................................................................................................... 4

2.1 Introduction ....................................................................................................4

2.2 Functional Classification Concepts...............................................................4

2.2.1 Access versus Mobility.........................................................................4

2.3 Other Important Factors Related to Functional Classification..................7

2.4 System Continuity ......................................................................................... 11

Section 3. Criteria............................................................................................................14

3.1 Definitions and Characteristics ................................................................... 14

3.1.1 Interstates ........................................................................................... 14

3.1.2 Other Freeways & Expressways ........................................................ 14

3.1.3 Other Principal Arterials ....................................................................15

3.1.4 Minor Arterials ....................................................................................15

3.1.5 Major and Minor Collectors.............................................................. 16

3.1.6 Local Roads ..........................................................................................17

3.2 Putting it all Together.................................................................................. 18

3.3 A Real World Example ................................................................................. 19

3.4 Final Considerations......................................................................................21

Section 4. Procedures .....................................................................................................25

4.1 Introduction ..................................................................................................25

4.2 Identifying the Functional Classification of a Roadway Network ...........25

4.2.1 Arterial Considerations .....................................................................27

4.2.2 Collector Considerations ...................................................................28

4.2.3 General Rules of Thumb for All Categories and the System as a 

Whole ..................................................................................................28

4.3 Good Practices...............................................................................................29

4.3.1 Ongoing Maintenance of the Functional Classification System ...29

4.4 Geographic Information Systems................................................................ 32

4.4.1 Proactive Communication and Accessibility of Information ........ 33

4.5 Partners in the Functional Classification Process ..................................... 33

4.5.1 Metropolitan Planning Organizations ............................................. 33

4.5.2 State DOTs..........................................................................................34

4.5.3 Counties and Other Agencies ...........................................................34

4.6 Suggested Procedural Tasks ........................................................................34

Section 5. Applications.................................................................................................. 40

5.1 Performance ..................................................................................................40

5.2 Data Needs and Reporting...........................................................................40

5.2.1 Impact of Functional Classification Changes ..................................40

5.3 Secondary Functional Classification Uses..................................................40

5.4 Highway Design............................................................................................ 41
Highway Functional Classification: Concepts, Criteria and Procedures

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5.4.1 The Relationship between Functional Classification and Design. 41

5.4.1.1 AASHTO Green Book and Flexibility in Highway Design 42

5.4.1.2 Livability ...............................................................................42

5.4.1.3 Smart Transportation Guidebook ......................................43

5.4.1.4 CSS in Designing Major Urban Thoroughfares for 

Walkable Communities.......................................................44

5.5 Assessment of Functional Classification Systems .....................................45

5.6 Emerging/Other Functional Classification Systems .................................45

5.7 Future Trends................................................................................................48

Section 6. Urban Boundaries ........................................................................................ 49

6.1 Introduction ................................................................................................. 49

6.2 Defining Urban and Rural............................................................................50

6.2.1 Census Definitions .............................................................................50

6.2.2 FHWA Definitions ........................................................................... 501

6.3 Relationship to Functional Classification...................................................52

6.4 Developing Adjusted Urban Area Boundaries ........................................... 53

6.4.1 Adjusted Urban Area Boundaries – Technical Tasks ..................... 53

6.4.2 Consideration Factors for Adjusting Urban Areas..........................54

6.5 Adjusted Urban Area Boundaries – Procedural Tasks ..............................58

6.5.1 Risk Factors to Urban Area Adjustment Schedule .........................58

6.5.2 Urban Area Adjustment Schedule....................................................59

6.6 Adjusted Urban Area Boundaries – Data Transmittal Requirements .....62

Section 7. Graphics Sources ...........................................................................................63
Highway Functional Classification: Concepts, Criteria and Procedures

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LIST OF TABLES

Table 2-1: Relationship between Functional Classification and Travel 

Characteristics ............................................................................................11

Table 3-1: Characteristics of Urban and Rural Arterials.............................................. 15

Table 3-2: Characteristics of Urban and Rural Minor Arterials .................................16

Table 3-3: Characteristics of Major and Minor Collectors (Urban and Rural) ......... 17

Table 3-4: Characteristics of Urban and Rural Local Roads .......................................18

Table 3-5: VMT and Mileage Guidelines by Functional Classifications - Arterials ..22

Table 3-6: VMT and Mileage Guidelines by Functional Classifications – Collectors 

and Locals ..................................................................................................23

Table 4-1: Example Massaschusetts Roadway Functional Classification Table........38

Table 4-2: Key Milestones for Development and Submittal of the Functional 

Classification Network............................................................................. 39

Table 5-1: Oregon DOT’s Classification System.......................................................... 45

Table 6-1: US Census Bureau Urban Area Types Defined by Population Range ...... 51

Table 6-2: FHWA Urban Area Types Defined by Population Range......................... 51

Table 6-3: Key Milestones for Development and Submittal of Adjusted Urban Area 

Boundaries ................................................................................................ 62

Table 6-4: Geospatial Database Required Attributes................................................. 62

LIST OF FIGURES

Figure 1-1: Principal Arterial - Other Freeways & Expressways ...................................2

Figure 1-2: HOV Lane on Interstate 95 in Woodbridge, VA........................................3

Figure 1-3: Other Principal Arterial in California ..........................................................3

Figure 2-1: Aerial View of the Eisenhower (and Johnson) Tunnels along I-70, west 

of Denver, CO ..............................................................................................5

Figure 2-2: View from Inside the Eisenhower Tunnel ..................................................5

Figure 2-3: Aerial View of Eisenhower Court, North Platte, NE ..................................5

Figure 2-4: Aerial View of Eisenhower Street in Carrolton, TX ................................. 6

Figure 2-5: Illustration of Access-Mobility Dynamic ................................................... 6

Figure 2-6: Collector Example .........................................................................................7

Figure 2-7: Example of Access Points .............................................................................7

Figure 2-8: Functional Classification Map of Giddings, TX and Surrounding 

Unincorporated Territory.........................................................................10

Figure 2-9: Schematic Illustrating the Concept of Continuity................................... 12

Figure 2-10: Example of an Exception to the Connectivity Guidelines, Wings Neck 

Road, Bourne, MA..................................................................................... 12

Figure 2-11: Example of an Interstate Spur Terminating at a City Street in Holyoke, 

MA .............................................................................................................. 13

Figure 3-1: Example of Interstate...................................................................................14

Figure 3-2: Example of Other Principal Arterial......................................................... 15

Figure 3-3: Example of Urban Minor Arterial ............................................................. 15
Highway Functional Classification: Concepts, Criteria and Procedures

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Figure 3-4: Federal Functional Classification Decision Tree......................................18

Figure 3-5: Map of an Urban Area’s Roadway Network..............................................19

Figure 3-6: Map of a Rural Area’s Roadway Network..................................................19

Figure 3-7: Worcester, MA Roadway System .............................................................. 20

Figure 3-8: Classification Overlap................................................................................. 21

Figure 4-1: Minnesota DOT Functional Classification Change Request Form......... 31

Figure 4-2: Example of Shifting due to Inconsistency between Tabular Event Data 

and Geospatial Data ..................................................................................32

Figure 4-3 Sample Roadway Color Scheme..................................................................33

Figure 4-4: Good-Practice Timeframe for Functional Classification Updates in 

Months .......................................................................................................35

Figure 5-1: “Table 5.1 Roadway Categories” from the Smart Transportation 

Guidebook, March 2008 ...........................................................................43

Figure 5-2: Community Arterial Roadway Design Guidelines in Smart 

Transportation Guidebook...................................................................... 44

Figure 5-3: Idaho DOT’s Proposed Redefinition of Functional Street Classifications

.................................................................................................................... 47

Figure 5-4: ITE Report: Context Sensitive Solutions in Designing Major Urban 

Thoroughfares for Walkable Communities ........................................... 47

Figure 6-1: Prototypical Urban and Rural Areas ......................................................... 50

Figure 6-2: Example of Roadway Coinciding with Adjusted Urban Area .................53

Figure 6-3: 2000 Census Urban Cluster and Urbanized Areas (Ohio and Vicinity) 54

Figure 6-4: Example Original Urban Area....................................................................55

Figure 6-5: Example Single Contiguous Area...............................................................55

Figure 6-6: Example Area Expanded to Cover Air Force Base .................................. 56

Figure 6-7: Example Area Expanded to Include Industrial Area .............................. 56

Figure 6-8: Example Boundary Adjusted to Align with Major Roadway ..................57

Figure 6-9: Example Boundary Adjusted for Simplicity .............................................57

Figure 6-10: Good Practice Level of Procedural Steps for an Urban Boundary 

Update Process ......................................................................................... 59
1

SECTION 1. INTRODUCTION

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. 

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. 

Over the years, functional classification has come to assume additional 

significance beyond its purpose as a framework for identifying the particular role 

of a roadway in moving vehicles through a network of highways. Functional 

classification carries with it expectations about roadway design, including its 

speed, capacity and relationship to existing and future land use development. 

Federal legislation continues to use functional classification in determining 

eligibility for funding under the Federal-aid program. Transportation agencies 

describe roadway system performance, benchmarks and targets by functional 

classification. As agencies continue to move towards a more performance-based 

management approach, functional classification will be an increasingly important 

consideration in setting expectations and measuring outcomes for preservation, 

mobility and safety.

As a result of the decennial census, the US Census Bureau issues urban area 

boundary maps. Transportation agencies should review these census boundaries 

and either accept them as is or adjust them for transportation planning purposes.

This guidance document provides recommended practices for assigning functional 

classifications and adjusting urban area boundaries concerning roadways that 

Federal, State and local transportation entities own and operate. Assigning 

functional classifications and adjusting urban area boundaries requires work 

elements common to many large-scale business enterprises: there are technical 

methods and tools to create an efficient and cost-effective end product; there are 

also procedural elements that require coordination and negotiation across 

agencies and individuals. This guidance document encompasses both of these 

elements.

This guidance document also recognizes and describes the implications of how our 

roadway systems are configured, used and planned for today:

 The Federal-aid system has matured significantly. A significant proportion of 

new functional classification designations are likely to occur from 

improvements and modifications to existing roads and corridors, rather than 

from designations on new roadways and corridors.
Highway Functional Classification: Concepts, Criteria and Procedures

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 In conducting functional classification updates, State departments of 

transportation (DOTs) strive for consensus with potentially dozens of 

agencies, including metropolitan and rural planning agencies, local officials 

and FHWA Division Offices.

 Geospatial technologies and travel demand forecasting capabilities have 

advanced significantly, greatly lowering the cost of data storage and increasing 

analysis capabilities.

 Planners and engineers have expanded roadway design options significantly, 

especially in areas where providing for non-motorized travel is a priority. 

Transportation agencies have developed their own classification terms to 

describe these options. 

1.1 Overview

This guidance document builds upon and updates the two most recent guidance 

documents circulated by FHWA, namely:

 Highway Functional Classification: Concepts, Criteria and Procedures, March 

1989

 Updated Guidance for the Functional Classification of Highways

Memorandum, October 14, 20081

1. All functional classification categories will now exist in both urban and 

rural areas. Specifically, all Principal Arterial sub-categories and all 

Collector sub-categories will be recognized in both urban and rural forms. 

The following revised functional classification categories should be used:

a. Principal Arterial

i. Interstate

ii. Other Freeways & Expressways (OF&E) (Figure 1-1)

iii. Other

(OPA)

b. Minor Arterial

c. Collector

i. Major 

Collector

ii. Minor 

Collector

d. Local

2. States should assign 

functional classifications

according to how the 

roadway is functioning in 

the current year only. 

With regard to future routes, roads should be functionally classified with 

 1 http://www.fhwa.dot.gov/policy/ohpi/hpms/fchguidance.cfm

Figure 1-1: Principal Arterial -

Other Freeways & Expressways 

Source: Ohio Statewide Imagery Program
Highway Functional Classification: Concepts, Criteria and Procedures

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the existing system if they 

are included in an 

approved Statewide 

Transportation 

Improvement Program

(STIP) and are expected to 

be under construction 

within the STIP timeframe 

of 4 years or less. Use the 

current classification for 

roadways, even 

replacement roadways that 

will upgrade the roadway, 

until construction is 

complete. Reclassify the new roadway once it has been constructed.

3. Ramps and other non-mainline roadways are to be assigned the same 

functional classification as the highest functional classification among the 

connecting mainline roadways served by the ramp. (Figure 1-2)

4. Principal Arterial roadways (Figure 1-3) serve a large percentage of travel 

between cities and other activity centers, especially when minimizing 

travel time and distance is important. For this reason, Arterials typically 

are roadways with high traffic volumes and are frequently the route of 

choice for intercity buses and trucks. The spacing of Arterials in urban 

areas is closely related to the trip-end density characteristics of activity 

centers in urban areas. The spacing of these facilities (in larger urban 

areas) may vary from less than 1 mile in highly developed central business 

areas to 5 miles or more in the sparsely developed urban fringes.

Figure 1-3: Other Principal Arterial in California

Source: Akos Szoboszlay

Principal Arterials play a unique role in providing a high degree of mobility and 

carrying a high proportion of travel for long distance trips. These facilities carry 

the major portion of trips entering and leaving an activity center, as well as the 

majority of through movements that either go directly through or bypass the area.

Roadways that fall 

into the Principal 

Arterials- Other 

Freeways &

Expressways category 

are limited-access 

roadways that serve 

travel in a similar way 

to the Interstates.

Transportation 

agencies apply a 

variety of treatments 

to preserve mobility 

and increase the 

person throughput of 

Urban Arterials, 

including ramp 

metering, highoccupancy-vehicle 

(HOV) lanes and highoccupancy toll lanes.

Figure 1-2: HOV Lane on 

Interstate 95 in Woodbridge, VA

Source: www.roadstothefuture.com
4

SECTION 2. CONCEPTS

2.1 Introduction 

This section of the guidance document presents the concepts underlying the 

functional classification of roadways. It first introduces the two primary 

transportation functions of roadways, namely mobility and access, and describes 

where different categories of roadways fall within a continuum of mobility-access. 

In addition to mobility and access, other factors that can help determine the 

proper category to which a particular roadway belongs — such as trip length, 

speed limit, volume, and vehicle mix — are discussed in this section. 

While Arterials, Collectors and Locals span the full range of roadway functions, 

the Federal functional classification scheme uses additional classification 

categories to describe these functions more precisely. Distinctions between accesscontrolled and full-access roadways; the urban and rural development pattern; and 

subtleties between “major” and “minor” sub-classifications are key considerations 

when determining the Federal functional classification category to which a 

particular roadway belongs. The process of determining the correct functional 

classification of a particular roadway is as much art as it is science. Therefore, a 

real-world example is presented to help make the discussion of functional 

classification more readily understood.

2.2 Functional Classification Concepts

Most travel occurs through a network of interdependent roadways, with each 

roadway segment moving traffic through the system towards destinations. The 

concept of functional classification defines the role that a particular roadway 

segment plays in serving this flow of traffic through the network. Roadways are 

assigned to one of several possible functional classifications within a hierarchy

according to the character of travel service each roadway provides. Planners and 

engineers use this hierarchy of roadways to properly channel transportation 

movements through a highway network efficiently and cost effectively. 

2.2.1 Access versus Mobility

Roadways serve two primary travel needs: access to/egress from specific locations 

and travel mobility. While these two functions lie at opposite ends of the 

continuum of roadway function, most roads provide some combination of each. 

 Roadway mobility function: Provides few opportunities for entry and exit and 

therefore low travel friction from vehicle access/egress

 Roadway accessibility function: Provides many opportunities for entry and 

exit, which creates potentially higher friction from vehicle access/egress

The flow of traffic 

throughout a roadway 

network is similar to 

the flow of blood 

through the human 

circulatory system or 

the trunk and branch 

system of a tree. The 

units moving through 

the system (blood 

cells, nutrients, 

vehicles, etc.) move 

through progressively 

smaller network 

elements as they 

approach their 

destination.
Highway Functional Classification: Concepts, Criteria and Procedures

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These two roles can be best understood by examining two extreme examples

(Figure 2-1 and Figure 2-2). 

First, consider the Eisenhower Tunnel west of Denver, CO. Located along 

Interstate 70, the Eisenhower Tunnel runs under the Continental Divide in the 

Rocky Mountains and is one of the longest tunnels in the United States. Motorists 

that travel through the tunnel are en route to a distant location and are using the 

roadway completely to serve their “mobility” needs. There is no location that is 

immediately “accessible” to the roadway. 

Next, consider the example of Eisenhower Court in North Platte, NE (Figure 2-3). 

This roadway is travelled almost exclusively by the individuals that live along the 

roadway. Hence, the roadway entirely provides “accessibility” and offers almost 

nothing in terms of mobility.

Figure 2-4 depicts the neighborhood around Eisenhower Street in Carrollton, TX.

This roadway serves both mobility needs (the residents that live along the side 

streets that intersect Eisenhower Street use it for some level of north/south 

mobility) and land access needs (there are both residential and commercial 

properties located along the roadway).

Figure 2-3: Aerial View of Eisenhower Court, North Platte, NE

Source: Google Earth Pro, June 27, 2012

Figure 2-1: Aerial View of the Eisenhower (and Johnson) 

Tunnels along I-70, west of Denver, CO

Source: Google Earth Pro, June 27, 2012

Figure 2-2: View from Inside the Eisenhower Tunnel

Source: Creative Commons Attribution-Share Alike 2.0 

generic license; Benjamin Clark
Highway Functional Classification: Concepts, Criteria and Procedures

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Figure 2-4: Aerial View of Eisenhower Street 

in Carrollton, TX

Source: Google Earth Pro, June 28, 2012

For nomenclature purposes,

those roadways that provide a 

high level of mobility are 

called “Arterials”; those that 

provide a high level of 

accessibility are called 

“Locals”; and those that 

provide a more balanced 

blend of mobility and access 

are called “Collectors.”

The relationship between 

mobility and land access is 

illustrated in Figure 2-5. 

Arterials provide mostly 

mobility; Locals provide mostly land access; and Collectors strike a balance 

between the two. Context Sensitivity and Livability form the environment through 

which Mobility and Access should be considered. These concepts are discussed in 

greater detail in Chapter 5.

While most roadways offer both “access to property” and “travel mobility” services, 

it is the roadway’s primary purpose that defines the classification category to 

which a given roadway belongs.2

 2 The use of the term “Local” roadway in the context of functional classification is separate from the use of 

the term in a jurisdictional context. While it is true that roadways functionally classified as “Local” are often 

under the jurisdiction of a “local” entity (i.e., incorporated city), Local Roads are not always under local 

jurisdiction. Other roadway classifications, including Arterials, may also be under the jurisdiction of a local 

(i.e., non-state) entity.

Figure 2-5: Illustration of Access-Mobility Dynamic

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

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2.3 Other Important Factors Related to Functional 

Classification

The distinction between “mobility and accessibility” is important in assigning 

functional classifications to roadways. There are a few additional factors to 

consider, and these are discussed here. 

Efficiency of Travel: Trip makers will typically seek out roadways that allow them 

to travel to their destinations with as little delay as possible and by the shortest 

travel time. Arterial roadways provide this kind of service, often in the form of 

fully or partially controlled access highways, with no or very few intersecting 

roadways to hinder traffic flow. Therefore, a high percentage of the length of a 

long-distance trip will be made on Arterials. In contrast, travelers making shorter 

trips tend to use Local and/or Collector roadways for a much higher proportion of 

the trip length than Arterial roads.

Collectors: As their name implies,

Collectors “collect” traffic from 

Local Roads and connect traffic to 

Arterial roadways. Collector routes 

are typically shorter than Arterial 

routes but longer than Local 

Roads. Collectors often provide 

traffic circulation within 

residential neighborhoods as well 

as commercial, industrial or civic 

districts (see Figure 2-6).

Access Points: Arterials primarily serve long-distance travel and are typically 

designed as either access controlled or partially access controlled facilities with 

limited locations at which vehicles can enter or exit the roadway (typically via onor off-ramps). In instances where limited or partial access control is not provided, 

signalized intersections are used to control traffic flow, with the Arterial given the 

majority of the green time. 

In growing urban areas, Arterial 

roadways often experience an 

ever-increasing number of 

driveway access points. This high 

degree of accessibility decreases 

mobility. To address this issue and 

restore the carrying capacity of 

through traffic on these roadways, 

transportation agencies apply 

access management principles, 

such as driveway consolidation

and median installations (see 

Figure 2-7).

In contrast, roadways classified as “Local” provide direct access to multiple 

properties.

A route is a linear 

path of connected 

roadway segments, all 

with the same 

functional 

classification 

designation. For 

example, the roadways 

along a given Arterial 

route may — and 

often do — comprise 

multiple named 

roadways or state 

numbered facilities. 

Similarly, different 

segments of a given 

named roadway, or 

even more likely a 

given state numbered 

route, may belong to 

different functional 

classification 

categories, depending 

on the character of 

travel service that 

each segment 

provides. In the 

example to the right, 

the minor Arterial 

“route” consists of a 

portion of Tyler Street 

and a portion of 

Dalton Avenue (shown 

in green). East of 

Dalton Avenue, Tyler 

Street (shown in 

brown) is a Minor 

Collector.

Figure 2-6: Collector Example

Source: CDM Smith

Figure 2-7: Example of Access Points

Source: Ohio DOT, 

http://www.ahtd.info/basic_bikef
Highway Functional Classification: Concepts, Criteria and Procedures

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Speed Limit: In general, there is a relationship between posted speed limits and 

functional classification. Arterials typically have higher posted speed limits as 

vehicles encounter few or no at-grade intersections. The absence of cross-traffic 

and driveways allows for higher rates of speed, which provides mobility, especially 

for long-distance travel. In contrast, because their primary role is to provide access, 

Locals are lined with intersecting access points in the form of driveways, 

intersecting roadways, cross walks and transfer points for buses and other modes. 

Due to the frequency of traffic turns, speed limits are kept low to promote safe 

traffic operations. Speed limits on any non-access controlled roadways are also 

influenced by the mix of vehicles and modes that use them. 

Route Spacing: Directly related to the concept of channelization of traffic 

throughout a network is the concept of distance (or spacing) between routes. For a 

variety of reasons, it is not feasible to provide Arterial facilities to accommodate 

every possible trip in the most direct manner possible or in the shortest amount of 

time. Ideally, regular and logical spacing between routes of different classifications

exists. Arterials are typically spaced at greater intervals than Collectors, which are 

spaced at much greater intervals than Locals. This spacing varies considerably for 

different areas; in densely populated urban areas, spacing of all routes types is

smaller and generally more consistent than the spacing in sparsely developed rural 

areas. Geographic barriers greatly influence the layout and spacing of roadways.

Usage (Annual Average Daily Traffic [AADT] Volumes and Vehicle Miles of 

Travel [VMT]): Arterials serve a high share of longer distance trips and daily 

vehicle miles of travel. In rural areas, Arterials typically account for approximately

half of the daily vehicle miles of travel; in urban areas, this percentage is often 

higher. Collectors account for the next largest percentage of travel. Urban Area 

Collectors account for somewhat less (5 to 15 percent), while the percentage for 

Rural Area Collectors is typically in the 20 to 30 percent range. Lastly, by 

definition, Local Roads in rural areas typically serve very low density, dispersed 

developments with relatively low traffic volume. In contrast, the Urban Local Road 

network, with higher roadway centerline miles and higher density spacing, serves 

denser land uses and therefore accounts for a larger proportion of travel than its 

rural counterpart.

While there is a general relationship between the functional classification of a 

roadway and its annual average daily traffic volume, two roads that carry the same 

traffic volume may actually serve very different purposes and therefore have 

different functional classifications. Conversely, two roadways in different parts of a 

State may have the same functional classification but carry very different traffic 

volumes. This is particularly applicable among urban areas with very different 

populations — an Arterial within a remote city with a population of 50,000 is 

likely to have a much lower traffic volume than an Arterial within a city of 1 million 

people.

Traffic volumes, however, can come into play when determining the proper 

functional classification of a roadway “on the border” of a functional classification 

group (for example, trying to determine whether a roadway should be classified as 

a Collector or Local). Furthermore, AADT can often be used as a “tie-breaker” 

when trying to determine which of two (or more) similar and roughly parallel 

roadways should be classified with a higher (or lower) classification than the 

other. For example, suppose that two parallel roadways appear to serve the 

When determining the 

functional 

classification of a 

given roadway, no 

single factor should be 

considered alone. For 

example, US 290 runs 

through the heart of 

Giddings, TX. Within 

the city, the roadway 

has many intersecting 

roadways, provides 

direct access to a 

number of densely 

developed commercial 

and residential 

properties and has 

speed limits as low as 

35 mph. However, 

because the roadway is 

one of the two most 

direct routes of travel 

between Austin and 

Houston and a large 

percentage of its 

traffic consists of 

longer distance trips, 

the roadway is best 

classified as an 

Arterial. 
Highway Functional Classification: Concepts, Criteria and Procedures

9

function of a Collector. Classifying both of them as a Collector could lead to 

undesirable redundancy in the functional classification network. All other things 

being equal, the roadway with the higher AADT would generally be given the 

Collector classification, while its companion would be given a Local classification

(Figure 2-8).
Highway Functional Classification: Concepts, Criteria and Procedures

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Figure 2-8: Functional Classification Map of Giddings, TX and Surrounding Unincorporated Territory

Source: Texas DOT, Transportation Planning and Programming Division, Data Analysis, Mapping and Reporting Branch, September 16, 2008
Highway Functional Classification: Concepts, Criteria and Procedures

11

Number of Travel Lanes: Roadways are designed and constructed according to 

their expected function. If a roadway is expected to function as an Arterial, it is 

designed for high capacity, with multiple travel lanes. In general, Arterials are 

more likely to have a greater number of travel lanes than Collectors, and Collectors 

are more likely to have a greater number of travel lanes than Locals. It should also 

be noted that the relationship between functional classification and number of 

lanes is stronger in urban areas than it is in rural areas.

Regional and Statewide Significance: Highly significant roadways connect large

activity centers and carry longer-distance travel between and through regions and 

States. Arterials carry the vast majority of trips that travel through a given State, 

while Local Roads do not easily facilitate statewide travel.

Table 2-1 summarizes the relationship between the factors previously described 

and the three broad categories of functional classification.

Table 2-1: Relationship between Functional Classification and Travel Characteristics

Functional 

Classification

Distance 

Served 

(and 

Length of 

Route)

Access 

Points

Speed 

Limit

Distance 

between 

Routes

Usage 

(AADT 

and 

DVMT) Significance

Number 

of Travel 

Lanes

Arterial Longest Few Highest Longest Highest Statewide More

Collector Medium Medium Medium Medium Medium Medium Medium

Local Shortest Many Lowest Shortest Lowest Local Fewer

2.4 System Continuity

Because the roadway system is an interconnected network of facilities channeling

traffic in both directions from Arterials to Collectors, then to Locals and back 

again, the concept of continuity of routes is important to recognize. A basic tenet

of the functional classification network is continuity — a roadway of a higher 

classification should not connect to a single roadway of a lower classification.

3

Generally speaking, Arterials should only connect to other Arterials. However, 

there are exceptions to this guideline. Arterials can end or link to very large 

regional traffic generators or can connect to multiple parallel roads of lower 

functional classification that, together, provide the same function and capacity as 

an Arterial.

In Figure 2-9, the Arterials (represented by black lines) only connect to other 

Arterials. Collectors (represented by the red lines), only connect to Arterials or 

other Collectors. Lastly, Local Roads (represented by the green lines) can connect 

to any type of roadway.

Exceptions to the “connectivity” guideline exist. A Collector can serve a major 

residential community and — for topological or other constraining reasons —not 

connect at one end to another similar or higher classified roadway. Other examples 

can also be found, especially within coastal communities. Wings Neck Road in 

Bourne, MA (Figure 2-10) is a good example. Figure 2-11 is an example of an

Interstate spur terminating at a city street in Holyoke, MA.

 3 A higher functionally-classified road can “split” its traffic between two lower-level roads, with 

different levels of access and mobility. 

Exceptions to the 

“connectivity” 

guideline exist. There 

are locations where an 

Arterial can “dead 

end” and not connect 

to another Arterial. A 

common example is 

when an Arterial 

terminates at a 

regionally significant 

land use (such as an 

airport or military 

installation). Another 

example is a Collector

that serves a major 

residential community 

and, for topological or 

other constraining 

reasons, does not 

connect at one end to 

another similarly or 

higher classified 

roadway. Many other 

examples can also be 

found within coastal 

communities. Wings 

Neck Road in Bourne, 

MA (Figure 2-10) is a 

good example. Other 

obvious examples are 

Interstate spur routes 

(the highest type of 

Arterial, to be 

discussed in the 

following section) that 

terminate at a city 

street in the 

downtown of an urban 

area.
Highway Functional Classification: Concepts, Criteria and Procedures

12

Source: CDM Smith

Figure 2-9: Schematic Illustrating the Concept of Continuity

 Arterials

 Collectors

 Locals

Figure 2-10: Example of an Exception to the Connectivity Guidelines

Wings Neck Road, Bourne, MA 

Source: MassDOT, Office of Transportation Planning, Functional Classification Map

Collector
Highway Functional Classification: Concepts, Criteria and Procedures

13

Figure 2-11: Example of an Interstate Spur Terminating

at a City Street in Holyoke, MA

Source: Google Earth Pro, June 29, 2012
14

SECTION 3. CRITERIA

3.1 Definitions and Characteristics

The previous section provided a general overview of the functional classification 

categories of Arterial, Collector and Local. For Federal functional classification

purposes, this section breaks these categories down further to stratify the range of 

mobility and access functions that roadways serve. Additionally, the physical 

layout and the official designation of some roadways dictate the classification of 

certain roadways.

3.1.1 Interstates

Interstates are the highest classification of Arterials and were designed and 

constructed with mobility and long-distance travel in mind. (Figure 3-1) Since 

their inception in the 1950’s, the Interstate System has provided a superior network 

of limited access, divided highways offering high levels of mobility while linking 

the major urban areas of the United States. 

Determining the functional 

classification designation of many 

roadways can be somewhat subjective, 

but with the Interstate category of 

Arterials, there is no ambiguity. 

Roadways in this functional 

classification category are officially 

designated as Interstates by the 

Secretary of Transportation, and all 

routes that comprise the Dwight D. 

Eisenhower National System of 

Interstate and Defense Highways 

belong to the Interstate functional classification category and are considered 

Principal Arterials.

3.1.2 Other Freeways & Expressways

Roadways in this functional classification category look very similar to Interstates.

While there can be regional differences in the use of the terms ‘freeway’ and 

‘expressway’, for the purpose of functional classification the roads in this 

classification have directional travel lanes are usually separated by some type of 

physical barrier, and their access and egress points are limited to on- and off-ramp 

locations or a very limited number of at-grade intersections. Like Interstates, these 

roadways are designed and constructed to maximize their mobility function, and 

abutting land uses are not directly served by them.

Access control is a key 

factor in the realm of 

functional 

classification. All 

Interstates are 

“limited access” or 

“controlled access” 

roadways. The use of 

the word “access” in 

this context refers to 

the ability to access 

the roadway and not 

the abutting land 

use—these roadways 

provide no “access” to 

abutting land uses. 

Access to these 

roadways is controlled 

or limited to maximize 

mobility by 

eliminating conflicts 

with driveways and atgrade intersections 

that would otherwise 

hinder travel speed. 

Access to these 

roadways is limited to 

a set of controlled 

locations at entrance 

and exit ramps. 

Travelers use a much 

lower functionally 

classified roadway to 

reach their 

destination.

Figure 3-1: Example of Interstate

Source: CDM Smith
Highway Functional Classification: Concepts, Criteria and Procedures

15

3.1.3 Other Principal Arterials

These roadways serve major centers of 

metropolitan areas, provide a high degree of 

mobility and can also provide mobility 

through rural areas. Unlike their accesscontrolled counterparts, abutting land uses 

can be served directly. Forms of access for 

Other Principal Arterial roadways include 

driveways to specific parcels and at-grade 

intersections with other roadways. (Figure 

3-2) For the most part, roadways that fall 

into the top three functional classification 

categories (Interstate, Other Freeways & 

Expressways and Other Principal Arterials) provide similar service in both urban 

and rural areas. The primary difference is that there are usually multiple Arterial 

routes serving a particular urban area, radiating out from the urban center to serve 

the surrounding region. In contrast, an expanse of a rural area of equal size would 

be served by a single Arterial.

Table 3-1 presents a few key differences between the character of service that 

urban and rural Arterials provide.

Table 3-1: Characteristics of Urban and Rural Arterials

Urban Rural

• Serve major activity centers, highest 

traffic volume corridors and longest trip 

demands

• Carry high proportion of total urban 

travel on minimum of mileage

• Interconnect and provide continuity for 

major rural corridors to accommodate 

trips entering and leaving urban area 

and movements through the urban 

area

• Serve demand for intra-area travel 

between the central business district 

and outlying residential areas

• Serve corridor movements having trip 

length and travel density characteristics 

indicative of substantial statewide or 

interstate travel

• Connect all or nearly all Urbanized 

Areas and a large majority of Urban 

Clusters with 25,000 and over 

population

• Provide an integrated network of 

continuous routes without stub 

connections (dead ends)

3.1.4 Minor Arterials

Minor Arterials provide service for trips of 

moderate length, serve geographic areas that 

are smaller than their higher Arterial 

counterparts and offer connectivity to the 

higher Arterial system. In an urban context, 

they interconnect and augment the higher 

Arterial system, provide intra-community 

continuity and may carry local bus routes. 

(Figure 3-3)

Figure 3-2: Example of 

Other Principal Arterial

Source: CDM Smith

Figure 3-3: Example of 

Urban Minor Arterial

Source: Unsourced photo
Highway Functional Classification: Concepts, Criteria and Procedures

16

In rural settings, Minor Arterials should be identified and spaced at intervals 

consistent with population density, so that all developed areas are within a 

reasonable distance of a higher level Arterial. Additionally, Minor Arterials in rural 

areas are typically designed to provide relatively high overall travel speeds, with 

minimum interference to through movement. The spacing of Minor Arterial 

streets may typically vary from 1/8- to 1/2-mile in the central business district 

(CBD) and 2 to 3 miles in the suburban fringes. Normally, the spacing should not 

exceed 1 mile in fully developed areas (see Table 3-2).

Table 3-2: Characteristics of Urban and Rural Minor Arterials

Urban Rural

• Interconnect and augment the higherlevel Arterials

• Serve trips of moderate length at a 

somewhat lower level of travel 

mobility than Principal Arterials

• Distribute traffic to smaller geographic 

areas than those served by higher-level 

Arterials

• Provide more land access than 

Principal Arterials without penetrating 

identifiable neighborhoods

• Provide urban connections for Rural 

Collectors

• Link cities and larger towns (and other 

major destinations such as resorts 

capable of attracting travel over long 

distances) and form an integrated 

network providing interstate and intercounty service

• Be spaced at intervals, consistent with 

population density, so that all 

developed areas within the State are 

within a reasonable distance of an 

Arterial roadway

• Provide service to corridors with trip 

lengths and travel density greater than 

those served by Rural Collectors and 

Local Roads and with relatively high 

travel speeds and minimum 

interference to through movement

3.1.5 Major and Minor Collectors

Collectors serve a critical role in the roadway network by gathering traffic from 

Local Roads and funneling them to the Arterial network. Within the context of 

functional classification, Collectors are broken down into two categories: Major 

Collectors and Minor Collectors. Until recently, this division was considered only 

in the rural environment. Currently, all Collectors, regardless of whether they are 

within a rural area or an urban area, may be sub-stratified into major and minor

categories. The determination of whether a given Collector is a Major or a Minor 

Collector is frequently one of the biggest challenges in functionally classifying a 

roadway network.

In the rural environment, Collectors generally serve primarily intra-county travel 

(rather than statewide) and constitute those routes on which (independent of 

traffic volume) predominant travel distances are shorter than on Arterial routes. 

Consequently, more moderate speeds may be posted.

The distinctions between Major Collectors and Minor Collectors are often subtle. 

Generally, Major Collector routes are longer in length; have lower connecting 

driveway densities; have higher speed limits; are spaced at greater intervals; have 

higher annual average traffic volumes; and may have more travel lanes than their 
Highway Functional Classification: Concepts, Criteria and Procedures

17

Minor Collector counterparts. Careful consideration should be given to these 

factors when assigning a Major or Minor Collector designation. In rural areas, 

AADT and spacing may be the most significant designation factors. Since Major 

Collectors offer more mobility and Minor Collectors offer more access, it is 

beneficial to reexamine these two fundamental concepts of functional 

classification. Overall, the total mileage of Major Collectors is typically lower than 

the total mileage of Minor Collectors, while the total Collector mileage is typically 

one-third of the Local roadway network (see Table 3-3).

Table 3-3: Characteristics of Major and Minor Collectors (Urban and Rural)

MAJOR COLLECTORS

Urban Rural

• Serve both land access and traffic 

circulation in higher density residential, 

and commercial/industrial areas

• Penetrate residential neighborhoods, 

often for significant distances

• Distribute and channel trips between 

Local Roads and Arterials, usually over 

a distance of greater than threequarters of a mile

• Operating characteristics include 

higher speeds and more signalized 

intersections

• Provide service to any county seat not 

on an Arterial route, to the larger 

towns not directly served by the higher 

systems and to other traffic generators 

of equivalent intra-county importance 

such as consolidated schools, shipping 

points, county parks and important 

mining and agricultural areas

• Link these places with nearby larger 

towns and cities or with Arterial routes

• Serve the most important intra-county 

travel corridors

MINOR COLLECTORS

Urban Rural

• Serve both land access and traffic 

circulation in lower density residential 

and commercial/industrial areas

• Penetrate residential neighborhoods, 

often only for a short distance

• Distribute and channel trips between 

Local Roads and Arterials, usually over 

a distance of less than three-quarters 

of a mile

• Operating characteristics include lower 

speeds and fewer signalized 

intersections

• Be spaced at intervals, consistent with 

population density, to collect traffic 

from Local Roads and bring all 

developed areas within reasonable 

distance of a Collector

• Provide service to smaller communities 

not served by a higher class facility

• Link locally important traffic generators 

with their rural hinterlands 

3.1.6 Local Roads

Locally classified roads account for the largest percentage of all roadways in terms 

of mileage. They are not intended for use in long distance travel, except at the 

origin or destination end of the trip, due to their provision of direct access to 

abutting land. Bus routes generally do not run on Local Roads. They are often 

designed to discourage through traffic. As public roads, they should be accessible 

for public use throughout the year. 
Highway Functional Classification: Concepts, Criteria and Procedures

18

Local Roads are often classified by default. In other words, once all Arterial and 

Collector roadways have been identified, all remaining roadways are classified as 

Local Roads (see Table 3-4). 

Table 3-4: Characteristics of Urban and Rural Local Roads

Urban Rural

• Provide direct access to adjacent land

• Provide access to higher systems

• Carry no through traffic movement

• Constitute the mileage not classified as 

part of the Arterial and Collector 

systems

• Serve primarily to provide access to 

adjacent land

• Provide service to travel over short 

distances as compared to higher 

classification categories

• Constitute the mileage not classified as 

part of the Arterial and Collector 

systems

3.2 Putting it all Together

The functional classification system groups roadways into a logical series of 

decisions based upon the character of travel service they provide. Figure 3-4

presents this process, starting from assigning the function of an Arterial by its 

level of access (limited or full) or Non-Arterial (full access).

Figure 3-4: Federal Functional Classification Decision Tree

Source: FHWA and CDM Smith

While this document emphasizes the importance of function and service over the 

urban/rural distinction when classifying roads, the classification process is still 

influenced by the intensity and distribution of land development patterns.

Classification of roadways in urban areas is typically guided by the local 

comprehensive planning and design process, or the fundamental principles of 

roadway functional classification. In comparison, rural development patterns are 

often more diverse, if not less orderly, thereby making the functional classification 

determination of some rural roadways more challenging (see Figure 3-5 and 

Figure 3-6).

All Roads

Arterial

Principal

Full Control

Interstate

Other 

Freeways & 

Expressways

Partial / 

Uncontrolled

Other 

Principal 

Arterial

Minor 

Non-Arterial

Collector

Major Minor

Local
Highway Functional Classification: Concepts, Criteria and Procedures

19

Figure 3-5: Map of an Urban Area’s Roadway Network

(Functional Classification more evident)

Source: CDM Smith

Figure 3-6: Map of a Rural Area’s Roadway Network

(Functional Classification less evident)

Source: CDM Smith

When comparing urban and rural areas, perhaps the most relevant characteristic is 

the density of the roadway network. Even with a cursory view of a map of an urban 

area’s roadway network, the functional classification of many roadways can be 

discerned due the differences in roadway size. In contrast, the functional 

classification of the roadway network in many rural areas is less readily apparent, 

primarily due to the relatively inconsistent roadway spacing.

Nevertheless, functional classifications should be assigned based on actual 

functional criteria, rather than the location of the roadway within an urban or 

rural context.

3.3 A Real World Example

At this point, the concepts, criteria and definitions of all Federal functional 

classification categories have been presented. However, to strengthen the 

functional classification practitioner’s understanding of these topics, the real 

world example of the city of Worcester, MA is presented below (Figure 3-7).
Highway Functional Classification: Concepts, Criteria and Procedures

20

1. The city of Worcester is served by two interstate routes, Interstate 190 and 

Interstate 290 (shown in black). These Interstates provide high mobility 

service to residential communities to the north, northeast and south sides 

of the city.

2. A handful of Other Freeways & Expressways and Other Principal Arterials

(shown in red and blue) radiate out from the central core of the city and 

provide direct service into, out of and through the city, offering 

connections to the surrounding areas not served by the Interstates.

3. An even larger number of Minor Arterials (shown in green) provide 

connectivity between the Interstate, Other Freeways & Expressways and 

Other Principal Arterials and are rather evenly spaced. Note that only a 

few of these Minor Arterial routes actually extend outside of the city 

border, as most of them terminate at Arterials within the city limits.

4. The Collector roadway system (shown in brown) consists of relatively 

shorter routes that mainly connect to Minor Arterials.

5. All other roadways (shown in gray) are Local Roads and comprise the vast 

majority of the mileage of the city’s roadway network.

Figure 3-7: Worcester, MA Roadway System 

Shaded area depicts the Urbanized Area

 
Highway Functional Classification: Concepts, Criteria and Procedures

21

3.4 Final Considerations

In many instances, assigning a functional classification to a roadway is 

straightforward, especially for Interstates and Locals. However, there is flexibility 

when deciding between adjacent classifications. For example, deciding whether a 

given roadway acts as a Minor Arterial or Major Collector can be subject to debate. 

Deciding between a Major Collector and Minor Collector assignment can be even 

more challenging. 

To assist transportation planners responsible for determining the functional 

classification of roadways, this guidebook offers a helpful tool that can make the 

classification process of classifying “borderline” roadways a bit easier. Table 3-5

illustrates the range of lane width, shoulder width, AADTs, divided/undivided 

status, access control and access points per mile by functional classification 

categories. 

Table 3-5 also presents guidelines for mileage and VMT ranges for Federal 

functional classifications of roads. These guidelines are based on an analysis of 

2008 HPMS data and are adjusted to represent reasonable ranges. The table 

presents mileage and VMT extents for rural states, urban states and all states. For 

this purpose rural states are defined as having 75 percent or less of their 

population in urban areas. Research determined this was a natural breakpoint that 

approximated the geographic difference between the States.

As expected, Interstates account for the lowest portion of total system miles, but 

the greatest portion of travel. Conversely, Local Roads comprise the greatest 

portion of system mileage with Collectors carrying the lowest percentage of travel 

volume. Therefore, as a primary consideration in functional classification, 

planners and engineers can use mileage as a guideline. Where roadway systems 

significantly deviate from these ranges, State DOTs should consider adjusting their 

roadway assignments during the functional 

classification review process and at least every 

10 years as part of the response to Census 

defined Urban Boundary changes. FHWA 

intends to review these guideline ranges for 

mileage and VMT periodically.

Lastly, as a result of variances within the 

functional classification system, the guidelines 

have overlapping ranges of values. This allows 

greater flexibility in determining functional 

classification (see Figure 3-8).

Figure 3-8: Classification Overlap

Source: FHWA

Arterial

Collector

Local

Areas of Uncertainty
Highway Functional Classification: Concepts, Criteria and Procedures

22

Table 3-5: VMT and Mileage Guidelines by Functional Classifications - Arterials

Arterials

Interstate Other Freeways & Expressway Other Principal Arterial Minor Arterial

Typical Characteristics

Lane Width 12 feet 11 - 12 feet 11 - 12 feet 10 feet - 12 feet

Inside Shoulder Width 4 feet - 12 feet 0 feet - 6 feet 0 feet 0 feet

Outside Shoulder Width 10 feet - 12 feet 8 feet - 12 feet 8 feet - 12 feet 4 feet - 8 feet

AADT1 (Rural) 12,000 - 34,000 4,000 - 18,5002 2,000 - 8,5002 1,500 - 6,000

AADT1 (Urban) 35,000 - 129,000 13,000 - 55,0002 7,000 – 27,0002 3,000 - 14,000

Divided/Undivided Divided Undivided/Divided Undivided/Divided Undivided

Access Fully Controlled Partially/Fully Controlled Partially/Uncontrolled Uncontrolled

Mileage/VMT Extent (Percentage Ranges)1

Rural System

Mileage Extent for Rural States2 1% - 3% 0% - 2% 2% - 6% 2% - 6%

Mileage Extent for Urban States 1% - 2% 0% - 2% 2% - 5% 3% - 7%

Mileage Extent for All States 1% - 2% 0% - 2% 2% - 6% 3% - 7%

VMT Extent for Rural States2 18% - 38% 0% - 7% 15% - 31% 9% - 20%

VMT Extent for Urban States 18% - 34% 0% - 8% 12% - 29% 12% - 19%

VMT Extent for All States 20% - 38% 0% - 8% 14% - 30% 11% - 20%

Urban System

Mileage Extent for Rural States2 1% - 3% 0% - 2% 4% - 9% 7% - 14%

Mileage Extent for Urban States 1% - 2% 0% - 2% 4% - 5% 7% - 12%

Mileage Extent for All States 1% - 3% 0% - 2% 4% - 5% 7% - 14%

VMT Extent for Rural States2 17% - 31% 0% - 12% 16% - 33% 14% - 27%

VMT Extent for Urban States 17% - 30% 3% - 18% 17% - 29% 15% - 22%

VMT Extent for All States 17% - 31% 0% - 17% 16% - 31% 14% - 25%

Qualitative Description (Urban)

• Serve major activity centers, highest traffic volume corridors, and longest trip demands

• Carry high proportion of total urban travel on minimum of mileage

• Interconnect and provide continuity for major rural corridors to accommodate trips 

entering and leaving urban area and movements through the urban area

• Serve demand for intra-area travel between the central business district and outlying 

residential areas

• Interconnect with and augment the principal arterials

• Serve trips of moderate length at a somewhat lower level of travel 

mobility than principal arterials

• Distribute traffic to smaller geographic areas than those served by 

principal arterials 

• Provide more land access than principal arterials without penetrating 

identifiable neighborhoods 

• Provide urban connections for rural collectors

Qualitative Description (Rural)

• Serve corridor movements having trip length and travel density characteristics 

indicative of substantial statewide or interstate travel 

• Serve all or nearly all urbanized areas and a large majority of urban clusters areas with 

25,000 and over population

• Provide an integrated network of continuous routes without stub connections (dead 

ends)

• Link cities and larger towns (and other major destinations such as 

resorts capable of attracting travel over long distances) and form an 

integrated network providing interstate and inter-county service

• Spaced at intervals, consistent with population density, so that all 

developed areas within the State are within a reasonable distance of 

an arterial roadway 

Provide service to corridors with trip lengths and travel density 

greater than those served by rural collectors and local roads and 

with relatively high travel speeds and minimum interference to 

through movement

1- Ranges in this table are derived from 2011 HPMS data.

2- For this table, Rural States are defined as those with a maximum of 75 percent of their population in urban centers. 
Highway Functional Classification: Concepts, Criteria and Procedures

23

Table 3-6: VMT and Mileage Guidelines by Functional Classifications – Collectors and Locals

Collectors Local

Major Collector2 Minor Collector2

Typical Characteristics

Lane Width 10 feet - 12 feet 10 - 11 feet 8 feet - 10 feet

Inside Shoulder Width 0 feet 0 feet 0 feet

Outside Shoulder Width 1 feet - 6 feet 1 feet - 4 feet 0 feet - 2 feet

AADT1 (Rural) 300 - 2,600 150 - 1,110 15 - 400

AADT1 (Urban) 1,100 - 6,3002 80 - 700

Divided/Undivided Undivided Undivided Undivided

Access Uncontrolled Uncontrolled Uncontrolled

Mileage/VMT Extent (Percentage Ranges)1

Rural System

Mileage Extent for Rural States3 8% - 19% 3% - 15% 62% - 74%

Mileage Extent for Urban States 10% - 17% 5% - 13% 66% - 74%

Mileage Extent for All States 9% - 19% 4% - 15% 64% - 75%

VMT Extent for Rural States3 10% - 23% 1% - 8% 8% - 23%

VMT Extent for Urban States 12% - 24% 3% - 10% 7% - 20%

VMT Extent for All States 12% - 23% 2% - 9% 8% - 23%

Urban System

Mileage Extent for Rural States3 3% - 16% 3% - 16%2 62% - 74%

Mileage Extent for Urban States 7% - 13% 7% - 13%2 67% - 76%

Mileage Extent for All States 7% - 15% 7% - 15%2 63% - 75%

VMT Extent for Rural States3 2% - 13% 2% - 12%2 9% - 25%

VMT Extent for Urban States 7% - 13% 7% - 13%2 6% - 24%

VMT Extent for All States 5% - 13% 5% - 13%2 6% - 25%

Qualitative Description (Urban)

• Serve both land access and traffic circulation in higher 

density residential, and commercial/industrial areas • Penetrate residential neighborhoods, often for 

significant distances

• Distribute and channel trips between local streets and 

arterials, usually over a distance of greater than three- quarters of a mile

• Serve both land access and traffic circulation in 

lower density residential, and 

commercial/industrial areas • Penetrate residential neighborhoods, often only 

for a short distance

• Distribute and channel trips between local 

streets and arterials, usually over a distance of 

less than three-quarters of a mile

• Provide direct access to adjacent land 

• Provide access to higher systems 

• Carry no through traffic movement

Qualitative Description (Rural)

• Provide service to any county seat not on an arterial 

route, to the larger towns not directly served by the 

higher systems, and to other traffic generators of 

equivalent intra-county importance such as 

consolidated schools, shipping points, county parks, 

important mining and agricultural areas 

• Link these places with nearby larger towns and cities or 

with arterial routes

• Serve the most important intra-county travel corridors

• Be spaced at intervals, consistent with 

population density, to collect traffic from local 

roads and bring all developed areas within 

reasonable distance of a minor collector • Provide service to smaller communities not 

served by a higher class facility 

• Link locally important traffic generators with 

their rural hinterlands

• Serve primarily to provide access to adjacent 

land • Provide service to travel over short distances 

as compared to higher classification 

categories

• Constitute the mileage not classified as part 

of the arterial and collectors systems

1- Ranges in this table are derived from 2011 HPMS data.

2- Information for Urban Major and Minor Collectors is approximate, based on a small number of States reporting. 

3- For this table, Rural States are defined as those with a maximum of 75 percent of their population in urban centers. 
Highway Functional Classification: Concepts, Criteria and Procedures

24

Mileage and Daily Vehicle - Miles of Travel (DVMT) Ranges: While these 

guidelines should be considered general rules of thumb, FHWA encourages State

DOTs to generate similar statistics for their roadway network and evaluate whether 

they fall within the normal ranges presented here. States should also apply the 

urban and rural guidelines as appropriate to their urban and rural areas.

Annual Average Daily Traffic: Roadway traffic volumes are typically expressed as 

annual average daily traffic (AADT) and represent one of the most objective 

characteristics of a roadway’s usage, providing a standard, easy to understand and 

simple metric for comparing the relative importance of roadways. In general, the 

higher the traffic volume is, the higher the functional classification will be (relative 

to the norms in the surrounding area). Therefore, examining the AADT with other 

roadways in both the immediate vicinity (and in the region as a whole) is helpful 

when deciding a “borderline” roadway classification. If, for example, when trying 

to determine whether a given roadway with an AADT of 3,500 should be classified 

as a Minor Arterial or Major Collector, most of the Minor Arterials (in the 

immediate area and the region at large) fall within the 4,000 to 10,000 range, and 

the Major Collectors fall within the 2,000 to 4,000 range, the roadway should be 

classified as a Major Collector.

The Big Picture: If there still remains some ambiguity surrounding what 

classification should be applied to a given roadway, it is often helpful to examine 

the roadways in close proximity to it and to consider the spacing. For example, if 

trying to determine whether a roadway should be classified as a Minor Arterial or 

Major Collector, it is useful to take a “step back” and determine whether any 

functional classification is under- or over-represented. If the area has a significant 

number of Minor Arterials, then the roadway could very well be best classified as a 

Major Collector. Alternatively, if there is not another Minor Arterial within a few 

mile radius of the roadway (assuming an urban context), then the roadway may 

best be designated as a Minor Arterial.

Even after careful review of a given roadway’s attributes, a small set of roadway 

segments that are difficult to classify can remain. For this reason, the set of 

mileage guidelines in Tables 3-5 and 3-6 can help provide high-level guidance 

regarding both the extent (mileage) and usage (daily vehicle miles of travel 

[DVMT]) of the roadway system that should fall into the different functional 

classification categories. While these guidelines have been developed for 

application at the State level, they can also be applied within regions. 

State DOTs are 

required to collect, 

analyze and publish 

traffic data on the 

roadways within their 

borders. Specifically, 

through the Highway 

Performance 

Monitoring System, 

each roadway segment 

on the Federal-aid 

highway (e.g., urban 

roadways classified as 

Minor Collectors and 

above and rural 

roadways classified as 

Major Collectors and 

above) is required to 

have an AADT value 

that is based on an

actual traffic count 

within the last3 years. 

Therefore, AADT is a 

readily available and 

objective metric that 

can be brought into 

the functional 

classification 

determination process.
25

SECTION 4. PROCEDURES

4.1 Introduction

This section of the guidance outlines suggested procedures for assigning 

functional classifications to highways, including a discussion of the specific 

technical tasks that describe the detailed technical “how to” tasks, as well as the

collaborative efforts with partner agencies to ensure the functional classification of 

the roadway network considers State, regional and local needs. Currently, each 

State maintains a categorized roadway network consistent with the Federal 

functional classification system. While functional classifications of some roadways 

can and do change over time, the functional classification of the vast majority of 

roadways remains stable. Consequently, the focus of each State’s efforts should be 

to identify roadways where the functionality has changed. These changes can take 

the form of newly constructed, re-aligned, extended, widened or otherwise 

reconfigured roadways. Equally important are changing land use and development 

patterns — growing residential areas, newly developed commercial or industrial 

centers and construction of isolated traffic generators can all have a profound 

impact on the roadway network serving these developments. State DOTs should 

establish, with local planning partners, a collaborative process of monitoring 

development and roadway usage patterns to ensure that the functional 

classification system is kept current. 

While the nation’s roadway system is mature in comparison to the 1960’s-era 

highway system, the concepts and processes pertaining to the original Federal 

functional classification system are still relevant. The following section briefly 

presents an adaptation of the key recommendations of the 1989 guidance 

document, which is based on an earlier 1960’s era document. 

Many State DOTs have generated their own functional classification guidance 

documents. For the most part, these State-specific documents are based upon 

FHWA’s 1989 document, augmented with additional details as necessary. To 

obtain a complete understanding of functional classification procedures in a 

particular State, these supporting documents should be reviewed as well. 

4.2 Identifying the Functional Classification of a 

Roadway Network

A primary objective of the functional classification system is to connect traffic 

generators (population centers, schools, shopping areas, etc.) with a roadway 

network that channelizes trips logically and efficiently. As classification proceeds 

from identifying Arterials to Collectors to Locals, the perspective (and size) of 

traffic generators also moves from a larger to a smaller scale (or from a smaller to a 

larger scale, if starting from the local development).

When developing a functional classification network in a given area, the same 

basic procedures should be followed, whether the functional classification is 

applied in a rural or an urban area. However, due to the differences in population 

Agencies can use 

travel demand models 

to validate or update 

their functional 

classification 

assignments. These 

models and the 

software they use 

produce estimates of 

the number of trips 

that travel between 

activity centers as well 

as the flows of travel 

on roadway segments. 

A particularly useful 

feature is “select link 

analysis” that shows 

the origin and 

destination location of 

travel from a roadway 

segment, and select 

zone analysis, which 

shows the path of trips 

from or to an activity 

center. Travel demand 

model “activity 

centers” represent 

collections of smaller 

areas such as block 

groups, census tracts 

or even counties, so 

their ability to track 

the path of travel from 

smaller areas is often 

limited. 
Highway Functional Classification: Concepts, Criteria and Procedures

26

and land development intensity between rural and urban areas, the process and 

considerations used to classify roadways may be different. Because functional 

classification is part art and part science, these procedures are a blend of detailed, 

task-oriented steps and qualitative guidelines. These procedures do not eliminate 

judgment from the classification process, but when used as a guide, they help to 

apply judgment in a sound and orderly fashion.

1. Identify traffic generators. In rural areas, traffic generators may be 

population centers (cities and towns); recreational areas such as lakes, 

national and State parks; military facilities; consolidated schools; and 

shipping points. In urban areas, traffic generators may be business 

districts; air, rail, bus and truck terminals; regional shopping centers; 

colleges and universities; hospital complexes; military bases; industrial 

and commercial centers; stadiums; fairgrounds; and parks. Regional 

traffic generators adjacent, but outside of the area of interest, should also 

be identified.

2. Rank traffic generators. Traffic generators should be categorized based 

on their relative ability to generate trips and be first stratified into urban 

and rural groupings. Traffic generators thought to be significant enough to

be served by a Major Collector or higher should be categorized into five to 

eight groups (it is better to have too many groups than to have too few, 

especially toward the lower end of the scale). Traffic generators with 

similar significance should be placed in the same group. These groups will 

be used to identify the functional classification of connecting roadways. 

Population, sales tax receipts, retail trade, visitation and employment are 

some examples of factors to consider when ranking traffic generations 

according to their significance.

3. Map traffic generators. Traffic generators should be mapped using 

graduated symbols of varying sizes and/or colors according to the group to 

which the generator belongs. This will produce a visual representation of 

the ranking. For example, the group of generators ranked highest should 

all be symbolized with the largest symbol.

4. Determine the appropriate functional classification to connect 

traffic generators. To determine the functional classification of 

roadways, work from the highest mobility facilities first by identifying 

Interstates, Other Freeways & Expressways, Other Principal Arterials, 

then Minor Arterials and Collectors (Major, then Minor). Then, by 

definition, Local Roads will be all of the roadways that were not classified 

as Arterials or Collectors. In other words, begin with a wide, regional 

perspective to identify Principal Arterials, then gradually move to smaller, 

more localized perspectives as Minor Arterials, Major Collectors and 

Minor Collectors are identified. In this process, consider the size of the 

traffic generators connected and the predominant travel distances and 

“travel shed”

4 served.

 4 “Travel shed” refers to the general area from which most travelers originate.
Highway Functional Classification: Concepts, Criteria and Procedures

27

4.2.1 Arterial Considerations

Arterials serve a wide range of functions across the access-mobility spectrum. 

Some considerations and rules of thumb for designating roads as Arterials include: 

 Start with Interstates and Other Freeways & Expressways. Control of access is 

perhaps the easiest criterion to apply, since roadways with full or partial 

control of access will most always be in the Arterial classification category. It 

is therefore advantageous to identify these roadways first, providing a 

convenient starting point in defining the Arterial system.

 Preserve the continuity of Principal Arterials (Interstates, Other Freeways & 

Expressways and Other Principal Arterials). Continuity of Principal Arterial 

routes traveling from rural areas, then into and through urban areas, should 

be preserved.

 Arterials should avoid neighborhoods. They often serve as buffers between 

incompatible land uses and should avoid penetration of residential 

neighborhoods.

 Most high volume roadways in urban areas function as Arterials. Notable 

exceptions to this rule in intensely developed area exist in cases where high 

volume roadways actually function as Collectors that serve traffic movements 

between Locals and Arterials or provide a high degree of direct access service 

to abutting land uses. For example, roadways that border on high-activity, 

low-land area generators may carry proportionally high volumes of traffic 

while functioning as Collectors.

 The network of Minor Arterial roadways will usually intersect roadways in all 

other classifications.

 In urban areas, guidance for distinguishing between Principal and Minor 

Arterials includes:

• Principal Arterials typically serve:

o Activity centers, from CBDs to larger town centers

o Important air, rail, bus and truck terminals

o Regional shopping centers

o Large colleges, medical complexes, military bases and other 

institutional facilities

o Major industrial and commerce centers

o Important recreational areas

• Principal Arterials provide more mobility; Minor Arterials provide more 

access. The land access function of Principal Arterials is subordinate to 

their primary function of providing mobility for traffic not destined to 

land adjacent to the roadway. Minor Arterials, on the other hand, have a 

slightly more important land access function (although even for this 

classification category, this is a secondary consideration).

• In general, the spacing between Principal Arterials should be greater than 

the spacing between Minor Arterials. In most cases, Minor Arterials will 

be located between Principal Arterials.
Highway Functional Classification: Concepts, Criteria and Procedures

28

• Minor Arterials in urban areas should provide service to all remaining 

major traffic generators not served by a Principal Arterial, and they 

provide adequate area-wide circulation.

• Location matters when assigning functional classification. Because traffic 

volumes in the outlying portions of an urban area are generally lower than 

in the more densely populated central areas, the traffic volume on a Minor 

Arterial in the central city may be greater than the volume on a Principal 

Arterial in a suburban area.

Note: Under MAP-21, the National Highway System (NHS) was expanded 

on October 1, 2012, to include the Principal Arterials at that time. This 

one-time event did not create a link between the NHS and Principal 

Arterials. A change to the Principal Arterials does not automatically 

change the NHS.

4.2.2 Collector Considerations

Collectors, which may have an important land access function, serve primarily to 

funnel traffic between Local to Arterial roadways. In order to bridge this gap, 

Collectors must and do provide access to residential neighborhoods. 

When deciding between Major and Minor Collectors, the following guidelines 

should be considered:

 A road that is not designated as an Arterial but that connects larger generators 

to the Arterial network can be classified as a Major Collector. Major Collectors 

generally are busier, have more signal-controlled intersections and serve more 

commercial development.

 Identify Minor Collectors for under-served residential areas. After Major 

Collectors have been identified, Minor Collectors should be identified for

clustered residential areas that have yet to be served by a roadway within 

higher classification categories. 

 In rural areas, Minor Collectors should have approximately equal distance 

between Arterial or Major Collector routes for equal population densities,

such that equitable service is provided to all rural areas of the State. The 

population density within each area bounded by an Arterial and/or Major 

Collector route can be determined, and the existing spacing of routes already 

selected can be measured. Areas with poor service can then be identified by 

comparing the data with a table of desirable Collector spacing (mileage 

between routes) versus population density. Additional routes can be added to 

the system as necessary.

4.2.3 General Rules of Thumb for All Categories and the 

System as a Whole

While working down through the functional classification system of roadway 

classifications, the following additional considerations should be kept in mind:

 Roadways that connect to and allow for the interchange of traffic with 

Principal Arterials are most likely to be Other Principal Arterials, Minor 

Arterials or Collectors.
Highway Functional Classification: Concepts, Criteria and Procedures

29

 Avoid, if possible, within spacing guidelines, assigning the same functional 

classification to parallel routes. In the event that parallel routes are 

determined to provide identical functions, a determination should be made as 

to which of the routes is more important (as perhaps indicated by traffic 

volumes); the other parallel route(s) will be assigned the next lower functional 

classification.

 In general, the more intense the development, the closer the spacing of 

roadways within the same functional classification category. In less dense 

suburban locations within an urban area, neighborhoods tend to be larger 

than in the more dense central parts of cities. These less dense areas generally 

do not require the same close spacing of facilities to serve traffic as the areas 

closer to the central business district.

 For the most part, a single connection between two generators is all that is 

required. However, in some instances, an additional alternative route might 

be included where:

• Two apparently alternative routes are separated by geographic barriers and 

each is needed for connection to another intermediate generator or another 

intersecting route within the same classification category

• One roadway excludes commercial vehicles

• Total traffic volume is not adequately handled by one of the roadways

• One roadway is tolled

 Ensure that each route terminates at a route of the same or higher functional 

classification. As each subsequent category in the functional classification 

hierarchy is identified and added to the system, the continuity of the system 

must be maintained. 

 In rural, sparsely developed areas, the spacing of various functional 

classification categories is often not a helpful criterion in determining 

functional classification.

In most cases, the most direct, most improved and most heavily traveled 

route should be chosen for connecting medium and small size traffic 

generators. 

4.3 Good Practices

The following section discusses and recommends a series of good practices that 

State DOTs may follow to keep the functional classification of its roadways as 

accurate as possible.

4.3.1 Ongoing Maintenance of the Functional Classification 

System

State DOTs are charged with ensuring that the functional classification of their

roadways is kept up-to-date. In addition, FHWA recommends that States update 

their functional classification system continually as the roadway system and land 

use developments change. States should also consider reviewing their systems 

every 10 years to coincide with the decennial census and the adjusted urban area 

boundary update cycle. 

FHWA encourages 

States to develop their 

own more detailed and 

more quantifiable 

guidelines. The state 

of Wisconsin has 

developed robust 

algorithms taking into 

account factors of the 

population of the 

areas connected by a 

roadway, land use, 

spacing and current 

AADT volumes. 
Highway Functional Classification: Concepts, Criteria and Procedures

30

This maintenance process involves ongoing coordination with local planning 

partners to identify roadways that require changes to their functional 

classification, due to changes in transportation network and/or land use patterns.

These changes can involve:

 Adding newly constructed or extended roadways to the network, which can in 

turn affect the functional classification of connecting or nearby roadways

 Upgrading the functional classification of an existing roadway due to land use 

changes or an improvement made to the roadway

 Downgrading the functional classification of an existing roadway due to land 

use changes, traffic controls that discourage through traffic or other controls 

that limit the speed and capacity of a road

Actively maintaining the functional classification attributes of roadways will 

reduce the level of effort needed for the periodic updates. As State DOTs work 

with their local transportation planning partners on various initiatives such as 

long-range planning activities and project programming and development, issues 

related to the functional classification should be kept in mind. Useful questions to 

ask are the following:

 Have new significant roadways been constructed that may warrant Arterial or 

Collector status?

 Has any previously non-divided Principal Arterial roadway been reconstructed 

as a divided facility?

 Has any new major development (such as an airport, regional shopping center 

major medical facility) been built in a location that has caused traffic patterns 

to change?

 Has there been significant overall growth that may have caused some 

roadways to serve more access or mobility needs than they have previously?

 Have any Arterial or Collector roadways been extended or realigned in such a 

way to attract more through trip movements?

 Has a particular roadway experienced a significant growth in daily traffic 

volumes?

A key success factor for State DOTs is to have a well-documented process for 

changing the functional classification of an existing roadway. This process, along 

with a description of what the functional classification is and why it is important, 

should be readily accessible on the internet.

Many State DOTs have developed a functional classification change request form

(see Figure 4-1). These forms ensure that consistent information and evidence 

supporting such a change are provided. Typically, information — such as the 

roadway location, the justification for the change and letters or signatures 

expressing local support — is required. 
Highway Functional Classification: Concepts, Criteria and Procedures

31

Figure 4-1: Minnesota DOT Functional Classification Change Request Form

Source: Minnesota DOT, Functional Classification, Request to Change Classification;

http://www.dot.state.mn.us/roadway/data/docs/Single_FC_Change_Form.pdf

When new Local Roads get added to the State’s roadway inventory databases, as a 

good practice, State DOTs should evaluate how closely their roadways fit within 

each functional classification category based on the percentage guidelines found 

in Tables 3-5 and 3-6. If any significant differences are found, steps may be taken to 

either correct or explain them. However, this refinement process should not be 

conducted simply to keep adding or removing roadways until certain percentage 

guidelines are met. Bearing in mind that the classification process is as much art 

and science, it should still be as systematic, reproducible and logical as possible. 

Additionally, states and their planning partners (to be discussed later) should 

document their methodology and attempt to follow it as consistently as possible.
Highway Functional Classification: Concepts, Criteria and Procedures

32

4.4 Geographic Information Systems

Transportation agencies rely on a variety of up-to-date spatial data to carry out 

their planning, maintenance and operations responsibilities. The most important 

element of this, for functional classification purposes, is an accurate GIS-based 

inventory of all roadways for a given area. This inventory contains the current 

functional classification of all roadways and AADT estimates to calculate daily 

VMT.5 Total mileage and total DMVT can then be calculated for the entire 

network, independent of functional classification, thereby providing the 

denominator for the mileage and DVMT percentages by functional classification.

State DOTs identify new roadways and roadway improvements in their Statewide 

Transportation Improvement Program (STIP). DOTs should maintain basic 

information such as mileage, functional classification, lanes and traffic forecasts 

in a Linear Referencing System/GIS format. A variety of other GIS data can be 

useful in the functional classification evaluation process — this includes land use, 

major traffic generators and digital ortho-photography.

As DOTs move toward integrated, enterprise-wide GIS-based asset management 

systems, it is becoming increasingly important to ensure consistency between 

traditional tabular roadway inventory data and geospatial databases representing 

the physical roadway network. Some State DOTs have been maintaining tabular 

databases that contain information on the numerous attributes of a roadway (e.g., 

number of lanes, speed limit and functional classification). 

Figure 4-2 illustrates the potential consequences of an inconsistency between 

databases. The example shows the merging of a GIS network and an underlying 

database containing functional class information. Because the network, as

represented in the GIS system, does not correlate completely with the roadway 

section representation of the non-GIS database, the displayed non-GIS database

information appears to be inaccurate.

Figure 4-2: Example of Shifting 

due to Inconsistency between Tabular Event Data and Geospatial Data

Source: CDMSmith

 5 Vehicle miles of travel can be calculated as: DVMT = length in miles * annual average daily 

traffic volume. 
Highway Functional Classification: Concepts, Criteria and Procedures

33

As shown above, GIS systems enable roadway segment color coding for validation 

and public display. An example of a color coding scheme for roadways by 

functional classification is shown in Figure 4-3. If followed, this suggestion would

improve future mapping consistency.

4.4.1 Proactive Communication and Accessibility of 

Information

State DOTs should create a 2-way communication network with internal and 

external users of functional classification information. The unit within the State 

DOT responsible for maintaining the official functional classification network 

should keep a list of internal and external users of functional classification 

information and provide them with guidance and a mechanism for updating 

functional classifications. Increasingly, enterprise-wide databases and information 

provided over the internet (either with static PDF maps or more sophisticated 

interactive, dynamic online mapping applications) allow end-users quick and 

convenient access to roadway attribute information, including functional 

classification. Additionally, internal linkages and strong lines of communication 

with the DOT offices responsible for asset management, system inventories and 

operations can ensure that updates and changes to their roadway databases are 

transferred to a master GIS inventory which the functional classification process 

has access.

4.5 Partners in the Functional Classification Process 

Whether processing a single functional classification change request or 

conducting a comprehensive statewide functional classification review in response 

to the establishment of the updated Adjusted Census Urban Boundaries, a variety 

of planning partners should be involved to ensure informed consent of the 

functional classification designation for a State’s roadways. 

4.5.1 Metropolitan Planning Organizations

MPOs are the primary local contact for the DOTs in Urbanized Areas. MPOs may 

initiate requests for revising the functional classification of a roadway within their 

planning area, either on their own initiative or on behalf of member jurisdictions. 

For requests originating from a member jurisdiction, the MPO may conduct an 

initial review to ensure compliance with functional classification criteria. Typically, 

MPOs will forward requests along with their recommendation for approval or 

disapproval to the State DOT unit responsible for maintaining the functional 

classification information. In some cases, local governments work directly with the 

State DOT, with concurrence from the MPO. 

Today’s geospatial 

technologies allow this 

data to be easily “viewed” 

in the context of a 

spatially accurate map 

display. Therefore, it is 

important that the 

linearly referenced 

tabular data, when 

integrated into a state 

DOT’s traditionally 

separated databases, be 

dynamically segmented 

on a routed roadway 

network and be spatially 

correct.

This issue may become 

apparent when roadways 

are mapped and 

symbolized according to 

their functional 

classification. The 

mapped functional 

classification 

designations often stop 

short or slightly 

overshoot their proper 

terminal location.

 Figure 4-3 Sample Roadway Color Scheme

Interstate 1

Other Freeways and Expressways 2

Other Principal Arterial 3

Minor Arterial 4

Major Collector 5

Minor Collector 6

Local 7

 
Highway Functional Classification: Concepts, Criteria and Procedures

34

4.5.2 State DOTs

For the sake of efficiency, a single specific unit with the DOT should be responsible 

for maintaining the official functional classification designation of all roads within 

the State. This unit should also be in charge of coordinating with FHWA on 

matters related to functional classification and be the final State decision-maker

for all functional classification issues. The unit should also ensure that all 

submissions for changes to the functional classification of a roadway have followed 

the appropriate documented procedures. If the State DOT approves a change, the 

unit should submit the change, along with supporting information, to the FHWA

Division Office for their review and approval. Upon receipt of FHWA approval (or 

disapproval), the DOT should notify the affected local jurisdiction of the decision.

DOT regional or district offices may be responsible for submitting system revisions 

for all State highways outside an MPO’s planning area and coordinating proposed 

system revisions for areas within the planning jurisdiction of an MPO.

Once a change has been approved by the FHWA Division Office, the State DOT 

may revise the official repository of functional classification information and 

update ancillary systems and work products to reflect the change.

4.5.3 Counties and Other Agencies

Counties may be responsible for initiating functional classification changes on 

roadways under their jurisdiction but outside of an MPO planning area. Counties 

within an MPO’s planning area should coordinate proposed system revisions with 

the MPO and submit any proposed changes to the State DOT.

In addition to MPOs, counties and State DOTs, other local government and 

regional entities — such as cities, rural transportation planning organizations, 

regional development commissions, councils of government, etc. — may also 

submit changes and participate in the update process. 

4.6 Suggested Procedural Tasks

This section of the guidance outlines a series of recommended technical and 

procedural steps to review the functional classification of a State’s roadway 

network. These tasks should be conducted through a collaborative effort between 

each State DOT and its local planning partners. In an ideal setting, the State and 

its partners should assess whether its roadways are properly classified on a 

continuous basis. Because new roads and major land development projects take

years of advance planning, State DOTs should anticipate and respond to functional 

class adjustments in tandem with development activity. Additionally, the entire 

network of roadways should be reviewed after the development of the adjusted 

urban area boundaries. For those State DOTs that actively maintain and update 

the functional classifications of their roadway system, this formal process should 

be rather straightforward. 

The following suggested procedures offer the most robust and detailed steps in the 

update process (Figure 4-4). Even for the most challenging of circumstances, the 

process of official review and submittal of the updated functional classification 

system can take less than 36 months to complete from the time of FHWA approval 

of the adjusted urban area boundaries.

State DOTs should 

complete the adjusted 

urban area boundary 

process within 2 years 

of the boundary 

release date.

The functional 

classification update 

should be completed 

within 3 years 

following the approval 

of the adjusted urban 

area boundaries.
Highway Functional Classification: Concepts, Criteria and Procedures

35

Figure 4-4: Good-Practice Timeframe for Functional Classification Updates in Months

Source: CDM Smith

States and their partners should re-evaluate the functional classification of the 

road system at least every 10 years, coinciding with the decennial census. FHWA 

highly recommends that this process be completed within 3 years of the formal 

approval of the adjusted urban area boundaries so that all States are coordinated 

with the same census. FHWA considers the State DOT to be the authority during 

this process and relies upon it to take an active leadership role.

FHWA Division Offices may correspond with State DOTs to formally launch the 

functional classification system review. This notice, which can accompany the 

approval of the adjusted urban area boundaries, reminds the State DOTs of their 

responsibilities and provide information regarding how and when the functional 

classification information should be submitted.

The following listing presents a good practice level functional classification review 

process with a 24 month completion timeframe, following approval of the adjusted 

urban area boundaries.

1. Mobilize the Functional Classification Update Process

a. Form a team to specifically guide the functional 

classification review and update process. Establish a 

functional classification review team composed of State and 

regional planners that have a vested interest in the final 

delineation of the functional classification designations. 

Individuals with experience in Federal transportation funding, 

highway design, traffic operations and the metropolitan 

transportation planning process should have a seat on the 

committee. This review team should be responsible for reviewing 

proposed changes to the functional classification network from 

local planning partners.
Highway Functional Classification: Concepts, Criteria and Procedures

36

b. Generate data, maps, etc. for use by local planning partners. 

Incorporate approved adjusted urban area boundaries in the 

enterprise GIS system and produce functional classification maps 

at a variety of scales that are relevant to local planning partners. 

These may include statewide, district, county and municipal 

scales.

c. Contact local planning partners. Contact various local 

planning partners to explain the task at hand and request their 

participation. MPO staff should be key partners, and other 

regional planning agencies, counties and/or local municipalities 

should be consulted as necessary. For many areas in which 

engaging local partners can be difficult, it is appropriate for State 

DOTs to be responsible for reviewing the functional classification 

of roadways.

2. Work with Local Planning Partners in the Functional Classification 

Review Process

a. Deliver data and documents to local planning partners. 

Transmit the maps described in #1b (and/or GIS data used to 

make such maps) to local planning partners. This transmittal 

should include specific instructions in terms of data formats, 

spatial accuracy, update processes and expected completion 

dates. The functional classification guidance document should 

also be shared with everyone involved in this process. A strong 

emphasis should be placed on transmitting the data in a timely 

fashion. In-person or video conference meetings can be extremely 

valuable to ensure proper communication and mutual 

understanding.

b. Work with Local Planning Partners. As necessary, a State DOT 

will work with the local planning partners to ensure that the 

functional classification review and update process meets their 

expectations. In urban areas, close collaboration with MPOs is 

extremely important. Regional workshops hosted by MPOs can 

be valuable in ensuring that there is a common understanding of 

the process and the schedule for delivery. While the exact details 

surrounding information exchange may vary from state to state, 

the local planning partners are generally expected to review the 

current functional classification network, in the context of the 

newly revised adjusted urban area boundaries, and submit a set 

of proposed changes to the functional classification of roadways 

in their area. Whether a large or minimal number of changes, 

sufficient explanation should be provided to justify each 

recommended functional classification change (see Table 3-1: 

Characteristics of Urban and Rural Arterials for examples). In 

many areas, proposed functional classification changes require 

formal MPO approval.
Highway Functional Classification: Concepts, Criteria and Procedures

37

3. Make Functional Classification Changes 

a. Gather, review and incorporate all proposed changes. The 

State DOT must review a local or regional transportation agency’s

proposed changes to ensure that they are reasonable. Special 

attention should be paid to the consistency of classifications at 

regional boundaries, overall route continuity, spacing and mileage

and DVMT percentage guidelines. In addition, DOTs should 

coordinate with neighboring States to ensure consistency at State 

boundaries. If possible, potential system-wide changes should be 

made in a “test” environment to avoid affecting the official 

enterprise system during the analysis of proposed changes. 

Follow-up meetings may be necessary to resolve issues discovered 

by the DOT.

b. Submit draft functional classification network information 

to FHWA. Once the State DOT has successfully reviewed and 

concurred with all recommend functional classification changes, 

it should submit the draft final functional classification network 

to its FHWA Division Office for final approval. The specific 

geospatial format of data delivery should be worked out between 

the State DOT and its FHWA Division. Separately, hard copy 

maps at a scale sufficiently small enough to evaluate the 

functional classification network should be provided. Should the 

Division Office have any issues with the proposed functional 

classification network, the State DOT and the affected local 

planning entities should meet to decide upon a mutually 

agreeable solution. Note: Any changes to the National Highway 

System (NHS) will need to be coordinated with FHWA HQ Office 

of Planning, Environment and Realty. Approval of changes to the 

NHS happens in FHWA HQ, and the procedures for modifications 

are detailed in 23 CFR 470.

c. Incorporate Functional Classification Changes into 

Enterprise Systems Once FHWA approval has been received, 

any proposed functional classification changes should be made 

into the enterprise database systems that house the official 

records of roadway functional classification. These functional 

classification changes should be forwarded to FHWA HEPP for 

inclusion into the HEPGIS database and also be incorporated into 

the June 15th HPMS data transmittal.
Highway Functional Classification: Concepts, Criteria and Procedures

38

An example functional classification table from Massachusetts can be found in Table 4-1. 

Table 4-1: Example Massaschusetts Roadway Functional Classification Table

Ref

# City/Town Roadway From To ExistingClassification

Proposed

Classification

Distance

(Miles) Map

1 Blandford Huntington 

Rd

Chester Rd / 

North St

Huntington Town 

Line

Rural Major 

Collector Local Road 3.80 1

Huntington

Blandford 

Hill Rd Route 20

Blandford Town 

Line

Rural Major 

Collector Local Road 0.83

2 Blandford

Cobble 

Mountain 

Rd

Russell 

Town Line

Birch Hill Rd Rural Major 

Collector Local Road 2.80

Blandford Birch Hill Rd Route 23

Cobble Mountain 

Rd

Rural Major 

Collector Local Road 0.24

Granville Wildcat Rd

Cobble 

Mountain 

Rd

Old Westfield Rd Rural Major 

Collector Local Road 1.94

Granville Phelon Rd North Lane 

#2

Cobble Mountain 

Rd

Rural Minor 

Collector Local Road 1.78

Granville

Cobble 

Mountain 

Rd

Phelon Rd Russell Town Line Rural Minor 

Collector Local Road 1.30

Russell

Cobble 

Mountain 

Rd

Blandford 

Town Line

Granville Town 

Line

Rural Major 

Collector Local Road 0.33

3 Chester Bromley Rd Huntington 

Town Line

4 Skyline Trail Local Road Rural Minor 

Collector 7 3.14

Huntington Bromley Rd Chester 

Town Line

Route 112 Local Road Rural Minor 

Collector 1.79

4 Huntington Country Rd Route 112 Route 66 Local Road Rural Major 

Collector 3.04

5 Holyoke Bobala Rd Whitney 

Ave

West Springfield 

Town Line

Local Road Urban Minor 

Collector 0.83 2

West 

Springfield

Interstate 

Dr

Holyoke 

Town Line Prospect Ave Local Road Urban Minor Collector 0.53

6

West 

Springfield

Prospect 

Ave

Westfield 

Town Line

Bernie Ave

Urban Minor 

Collector Local Road 2.18

West 

Springfield Morgan Rd Prospect Ave

Amostown Rd Urban Minor 

Collector Local Road 1.24

West 

Springfield

Amostown 

Rd Morgan Rd Pease Ave

Urban Minor 

Collector Local Road 0.65

Westfield Old Holyoke 

Rd

East 

Mountain 

Rd

West Springfield 

Town Line

Urban Minor 

Collector Local Road 0.60

Description of Changes

1. Huntington Road in the Town of Blandford and Blandford Hill Road in the Town of Huntington no longer provide access 

to through traffic. Additionally, portions of this roadway are unsurfaced. For this reason, it is recommended that this 

roadway be downgraded from a Rural Major Collector to a Local Road.

2. The Department of Homeland Security recently closed access to Cobble Mountain Road in the Town of Blandford in 

order to increase security of the Cobble Mountain Reservoir. Consequently, it is recommended that all roadways 

discussed in Reference #2 in Table 1 be downgraded to Local Roads due to the inaccessibility and lack of continuity of 

the roadway functional classification system.

Sample functional classification changes listed, with examples of supporting justification
Highway Functional Classification: Concepts, Criteria and Procedures

39

Table 4-2 presents good practice milestones for the overall development and 

submittal process.

Table 4-2: Key Milestones for Development and 

Submittal of the Functional Classification Network

Event

Month Following FHWA Adjusted Urban 

Area Boundary Approval

State DOT launches the formal functional 

classification update process after FHWA 

approves the State’s adjusted urban area 

boundaries

Month 1

State DOT works with planning partners 

to review and propose changes to the 

functional classification of its roadways

Months 2-17

State DOT gathers and processes all 

proposed function classification changes 

and submits draft final data and/or maps 

to FHWA Division Office for review

Months 18-20

DOT incorporates updates into planning 

process and related databases to ensure 

submittal of updated functional 

classification in upcoming June 15th

HPMS submittal

Months 22-24
40

SECTION 5. APPLICATIONS

5.1 Performance

This section of the guidance document details a variety of ways functional 

classification data may be used by Federal, State, local and other entities. 

Transportation agencies organize many of their administrative, budgetary, 

operations and maintenance activities around functional classification. 

Functional classification is also an important organizing element in data 

management and highway statistics reporting.

Currently, Federal and State funding programs assign a substantial share of 

capital and operating resources to the Principal Arterial system, in comparison to 

lower functional classifications. Likewise, expectations for condition and 

performance tend to be higher for the higher functional classifications. There is 

risk associated with not investing in and maintaining the system that carries the 

most people and goods.

5.2 Data Needs and Reporting 

Statistics derived from the Federal roadway databases are organized around 

functional classification. This data are used in a number of ways, including

reporting on the condition of the nation’s roadways to Congress and in other 

highway statistics reports and studies. 

5.2.1 Impact of Functional Classification Changes

The changes brought about in the functional classification categories with this 

updated guidance document will lead to more uniform and more accurate 

classification of roadways across the country. This will improve the tracking, 

monitoring and reporting on the performance of the system and specific system 

elements at a national and State level.

5.3 Secondary Functional Classification Uses

Functional classification is used by transportation agencies in a number of ways,

from design to maintenance. The hierarchal system correlates the purpose of a 

roadway with all the external factors transportation agencies handle. The 

functional classification of a roadway is often a factor in decision-making by 

transportation agencies.

 Program and Project Prioritization – In a climate of constrained 

resources, functional classification often plays a role in the prioritization of 

expenditures. Several transportation agencies have developed separate 

funding programs to support the roadway systems that serve their longest 

distance travel, a large proportion of which comprises the Principal Arterial 

system. 

 Asset Management – Functional classification plays a role in transportation 

agencies’ asset management programs, as agencies generally work to preserve 
Highway Functional Classification: Concepts, Criteria and Procedures

41

and protect their most important assets — those that serve the most people 

and goods. 

 Safety Programs – Functional classification is used by transportation 

agencies to evaluate the safety of their roadways and implement safety 

improvement programs. Agencies consider the type of roadway in evaluating 

the significance of crash rates. The typical safety improvement may also vary 

widely depending on the functional classification of a roadway. For example, 

speed reduction or signage improvements may be more effective in reducing 

crashes on a Local Road than on an Arterial.

 Highway Design – There is a correlation between functional classification 

and design. As an illustration, lower class roadways have lower speed limits, 

narrower lanes, steeper curves, etc., while higher class roadways have higher 

speed limits, wider lanes and fewer sharp curves. The relationship between 

functional classification and highway design is discussed in the following 

section (Subsection 5.4.1).

 Bridge programs – Functional classification often plays a key role in a 

States’ bridge program. For example, some States have set thresholds, such as

a functional classification of Local with low traffic volume, at which 1-lane 

bridges are acceptable. 

 Traffic control – Some transportation agencies may look to functional class 

to determine the most appropriate intersection control measure to use. 

 Maintenance – Functional classification often plays a role in resurfacing 

cycles, which is related to asset management and project prioritization. The 

classification of a roadway also impacts general maintenance and snow/ice 

removal in inclement weather. 

5.4 Highway Design

5.4.1 The Relationship between Functional Classification and 

Design

Functional classification does not dictate design; however, the two influence one 

another. There is a great deal of latitude in the design of a roadway relative to its

functional classification.

Transportation agencies may maintain their own roadway typology. But it is also 

important that the Federal functional classification system (e.g., FHWA reporting 

guidelines) be followed. Secondary roadway typologies developed by 

transportation agencies can be descriptive of how an agency wants vehicles to 

interact in different settings. Some States, for example, allow for local control over 

design standards in roadway-dense areas. This is essentially a form of context 

sensitive solutions (CSS).

6

 6 Context sensitive design describes a process and practice that considers the both the 

immediate environment of the roadway and the transportation needs of the communities it 

serves. For more information, see http://contextsensitivesolutions.org.
Highway Functional Classification: Concepts, Criteria and Procedures

42

The following presents a summary of key resources available on how functional

classification can work in concert with livable and walkable communities.

5.4.1.1 AASHTO Green Book and Flexibility in Highway Design

Although States’ design standards are often based on the AASHTO Green Book,

FHWA’s Flexibility in Highway Design document illustrates flexibility options for 

States to tailor their designs to incorporate community values while safely and 

efficiently moving people and goods.

The AASHTO Green Book and other design manuals recognize the relationship 

between highway functional classification and design criteria. The AASHTO Green 

Book states that, “The first step in the design process is to define the function that 

the facility is to serve. The level of service required to fulfill this function for the 

anticipated volume and composition of traffic provides a rational and cost effective 

basis for the selection of design speed and geometric criteria within the range of 

values available to the designer (for the specified functional classification). The use 

of functional classification as a design type should appropriately integrate the 

highway planning and design process.”

The Green Book explains that functional classification decisions are made well 

before an individual project is selected to move into the design phase. This 

decision is made on a system-wide basis by cities, counties or State DOTS or MPOs 

as part of their transportation planning process. Because these decisions require 

considerable lead time, the functional classification of a roadway often represents 

a decision made years before the road is built. After a functional classification has 

been assigned to a roadway, however, there is still a degree of flexibility in the 

major controlling factor of design speed. There are no “cookie-cutter” designs for 

roadways. Instead, there is a range of geometric design options available.

5.4.1.2 Livability

By FHWA definition, “Livability is about tying the quality and location of 

transportation facilities to broader opportunities such as access to good jobs, 

affordable housing, quality schools, and safe streets.” The term captures and 

recognizes the pervasive influence of transportation in our daily lives and provides 

a justification for transportation investments that address broader social goals 

such as quality of life. Specific investments include expanding the use of 

Intelligent Transportation System (ITS) technologies, quiet pavements and Travel 

Demand Management approaches in system planning and operations. 

FHWA’s Livability in Transportation Guidebook cautions that functional 

classification based designs may not be responsive to context. The report notes the 

traditional association of functional classification with the movement of vehicles, 

but it also notes the historical lack of recognition regarding the influence of land 

use density and mix on the feasibility and desirability of walking, as well as the 

influence of land use density and mix on setting operating speeds that are 

appropriate for the level of pedestrian activity present. The report describes 

corridor re-design initiatives that have preserved mobility for vehicles and 

enhanced access for travel by foot. These initiatives have produced, when 

considering all modes, including bicyclists, pedestrians, transit users, a more 

optimal outcome on the mobility-access continuum.
Highway Functional Classification: Concepts, Criteria and Procedures

43

5.4.1.3 Smart Transportation Guidebook

The Smart Transportation Guidebook: Planning and Designing Highways and 

Streets that Support Sustainable and Livable Communities, New Jersey and 

Pennsylvania Departments of Transportation, March 2008, recommends an 

approach to roadway planning and design that tailors transportation investments 

to the specific needs of each project. The ultimate goal of the guidebook is to 

integrate the planning and design of streets and highways in a manner that 

fosters development of sustainable and livable communities. The guidebook 

proposes a new roadway typology to design roadways that better reflect their role 

in the community and the larger transportation network. The typology (Table 5.1 

in the Smart Transportation Guidebook) is shown below as Figure 5-1. This 

scheme focuses more narrowly on the characteristics of access, mobility and 

speed. And, the guidebook emphasizes that this typology should be used only as a 

planning and design “overlay” for individual projects and should not replace the 

traditional functional classification system. 

Figure 5-1: “Table 5.1 Roadway Categories” 

from the Smart Transportation Guidebook, March 2008

Source: Pennsylvania Department of Transportation

The guide addresses design options for roadway attributes such as:

 Travel lane width

 A shift to designing for desirable operating speed versus design speed

 Shoulder width

 On-street parking

 Bicycle facilities

 Medians

 Intersections (including turn radii)

 Pedestrian facilities

 Landscaping

 Access and spacing

The guidebook describes seven prototypical development types and the design 

attributes appropriate for each, by roadway classification. The design options for 

a Community Arterial (row 2 from Figure 5-1 above) are shown in Figure 5-2.
Highway Functional Classification: Concepts, Criteria and Procedures

44

Many States and localities have adopted policies that aim to consider the needs of 

all roadway users. Such policies have been referred to as ‘Complete Streets’ 

policies. The PennDOT Smart Transportation Guide has been identified as a good 

example of addressing Complete Streets issues in the American Planning 

Association Report #559, “Complete Streets: Best Policy and Implementation 

Practices.”

Figure 5-2: Community Arterial Roadway Design Guidelines in Smart Transportation Guidebook

Source: Pennsylvania Department of Transportation

5.4.1.4 CSS in Designing Major Urban Thoroughfares for Walkable 

Communities

ITE’s Context Sensitive Solutions in Designing Major Urban Thoroughfares for 

Walkable Communities, 2006 is another valuable resource for practitioners. This 

report advances the successful use of context sensitive solutions in the planning 

and design of major urban thoroughfares for walkable communities. The 

document, which can be found at http://www.ite.org/bookstore/RP036.pdf,

provides guidance on how to apply CSS concepts and principles to create roadway 

improvement projects consistent with their physical settings. 

Specifically, this work describes the principles, benefits and importance of CSS in 

transportation projects; identifies how CSS principles can be applied in the 

planning and development of improvements to major urban thoroughfares; 

describes the relationship, compatibility and tradeoffs that may be appropriate 

when balancing the needs of users, adjoining land uses, environment and 

community interests; presents guidance on how to identify and select appropriate 

thoroughfare types and corresponding design parameters to best meet the needs 

of a particular context; and provides criteria for specific roadway elements along 

This guidance 

document can be 

found at: 

http://contextsensitiv

esolutions.org/conten

t/reading/dots_releas

e_smart_transportatio

n_guidebook/resourc

es/smart_transportati

on_guidebook/
Highway Functional Classification: Concepts, Criteria and Procedures

45

with guidance on balancing stakeholder, community and environmental needs 

and constraints.

5.5 Assessment of Functional Classification Systems

While the Federal functional classification categories play an important role in 

Federal, State, regional and local transportation planning, there is an emerging 

trend in transportation to develop new classification categories with which to 

group and describe roadways. At the heart of this trend is the recognition that 

roadways do more than move traffic. Roadways are the basic skeleton of a 

community and are travelways for other modes of transportation, including 

walking, bicycling and public transportation. The following section describes 

other functional classification systems in use and touches upon emerging concepts 

in the realm of roadway functional classification.

5.6 Emerging/Other Functional Classification 

Systems

While most States only use the FHWA functional classification scheme, several 

States have developed additional or alternative classification systems to suit their 

planning and engineering needs. Reasons for developing alternative functional 

systems include the need to incorporate unique roadway types or roadways that 

are not part of the Federal-aid system and the need to develop a system to meet 

the unique administrative or jurisdictional requirements of a State. 

Oregon DOT is one State that has employed a separate classification system. This 

alternate system has only four categories (Interstate, Statewide, Regional and 

District). While there is not a single translation to convert the Federal functional 

classification categories to the four State categories, Table 5-1 represents a general 

“rule of thumb” that Oregon DOT uses for the translation between the two 

systems.

7

Table 5-1: Oregon DOT’s Classification System

State Classification 

System (SCS) Description Corresponding Functional Classifications

Interstate Highways Provide connections to major cities, regions or 

other states; regional trips within metro areas. • Urban or Rural Interstate

Statewide Highways

Provide connection to larger urban areas, ports 

and recreational areas that are not directly 

served by interstate highways

• Principal Arterial – Other

• Urban Principal Arterial – Other 

Freeway Expressway

• Urban or Rural Other Principal Arterial

Regional Highways

Provide links to regional centers, statewide or 

interstate highways or economic or activity 

centers of regional significance

• Urban or Rural Minor Arterial

District Highways Facilities of county-wide significance function 

largely as county and city Arterials or Collectors

• Urban or Rural Minor Arterial

• Urban or Rural Major Collector 

• Rural Minor Collector

 7 Department of Transportation, Guidelines for Updating Federal Aid Urban Boundaries and 

Functional Classification, July 2003 

http://www.oregon.gov/ODOT/TD/TDATA/rics/docs/InstructionsForFCReview.pdf?ga=t
Highway Functional Classification: Concepts, Criteria and Procedures

46

With the institutionalization of new concepts such as sustainability, smart growth, 

new urbanism and complete streets comes a different perspective on

transportation as a whole and on roadways in particular. These movements have 

shifted the dialogue from the movement of automobiles to the mobility of persons.

Some States have developed roadway design guidelines that decouple the Federal 

functional classification system from the specific design needs of a roadway that 

are determined through a project development process. 

The MassDOT Project Development and Design Guide8

 provides designers with 

options that reflect the needs of a considerable range of prevailing land uses and 

roadway user types. While the guide notes the role that the Federal functional 

classification system plays in ensuring mobility, access and connectivity, as well as 

its role in determining funding eligibility, it also points out that MassDOT’s 

guidance on access control, cross-sections, sight distance, design speeds etc. 

reflect the appropriate level of flexibility that the department applies to roadway 

design. As an example, MassDOT provides ranges of acceptable design speeds 

based on roadway type (Arterial, Collector) and subtype, as well as area type 

(Rural, Suburban and Urban) and subtype. 

The Idaho DOT also embraces this new concept. The DOT’s August 2009 

Technical Report 5 entitled “Highway System Classification (Functional 

Classification)”9 states that the department has come to a new understanding 

that “streets should connect to their surrounding environment through 

adjustments in highway/street elements and functions.” This approach bucks the 

traditional ‘one size fits all’ approach to roadway design that has been effective in 

supporting vehicular mobility. 

The new approach of multimodal street design encompasses four distinct 

elements or zones (the travelway zone, the pedestrian zone, the context zone and 

the intersection zone). Each element works with the others to accommodate the 

needs of multiple modes in harmony their abutting land uses, taking into account 

environmental, historical preservation and economic development objectives. 

Idaho’s new functional street classification system is consistent with other 

national good practices which recognize the importance of the different 

transportation functions that are accommodated within the roadway’s right of 

way. Increasingly, municipal thoroughfare plans are breaking the traditional 

“Arterial, Collector, Local” mold and using alternate typology. These typologies 

expand the rural/urban construct into more granular categories that recognize 

aesthetic and neighborhood-level concerns and explicitly account for all modes of 

transportation.

Idaho’s proposed functional street classification system is consistent with other 

national practices, which are often found at the local level. Figure 5-3 illustrates 

the proposed multimodal functional street classification system (which includes 

 8 The MassDOT Project Development and Design Guide,

http://www.massdot.state.ma.us/highway/DoingBusinessWithUs/ManualsPublicationsForms/Pr

ojectDevelopmentDesignGuide.aspx

9 Technical Report 5, Highway System Classification, August 12, 2009, 

http://itd.idaho.gov/transportation-performance/lrtp/reports/Tech%20Rept%205-

Highway%20Systems%20Classification.pdf
Highway Functional Classification: Concepts, Criteria and Procedures

47

the categories of Freeways, Boulevards, Avenues and Streets) and relates it to the 

conventional street classification system. Idaho has other classes as well.

Figure 5-3: Idaho DOT’s Proposed Redefinition of Functional Street Classifications

Source: Idaho Department of Transportation

Idaho Department of Transportation Statewide Transportation Systems Plan

The broadening of road typologies and 

design options within the context of 

functional classification is not limited to a 

few DOTs. The Institute of Traffic 

Engineers’ Context Sensitive Solutions in 

Designing Major Urban Thoroughfares for 

Walkable Communities 10 supports and 

extends this way of thinking. (Figure 5-4) 

In addition, the ARTIST (Arterial Streets 

Toward Sustainability)11 concept and the 

United Kingdom’s Manual for Streets 12

offer new ways of categorizing roadways 

that support short-distance mobility and 

access with design options to 

accommodate a variety of modes and 

roadway treatment options.

 

10 Institute of Traffic Engineers, Context Sensitive Solutions in Designing Major Urban 

Thoroughfares for Walkable Communities, March, 2010.

11 Lund University, Department of Technology and Society, Arterial Streets Toward 

Sustainability, Sweden, http://www.tft.lth.se/english/research/traffic_safety/artists/?L=2

12 Department for Transport, Manual for Streets, March 29, 2007 

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/3891/pdfmanf

orstreets.pdf

Figure 5-4: ITE Report: Context 

Sensitive Solutions in Designing Major 

Urban Thoroughfares for Walkable 

Communities

 
Highway Functional Classification: Concepts, Criteria and Procedures

48

5.7 Future Trends

Additionally, a significant change is occurring in the transportation industry 

related to the development of improvement projects focusing on the performance 

of the facility. Roadway performance can be measured in a number of ways, 

including mobility, speed, safety and surface condition, as well as by person 

throughput and the accommodation of multiple transportation modes. 

Increasingly, the character and context of the environment within which the 

roadway is located, as well as the expectation of its performance on a number of 

measures, are driving the design of roadway improvement projects. Gone are the 

days of simply verifying a roadway’s functional classification and applying a “onesize-fits-all” approach to the application of design standards of a roadway 

improvement project. 

This movement in transportation planning to categorize roadways beyond the 

traditional “Arterial, Collector, Local” spectrum will continue to evolve. 

Continuing research and dialogue among transportation practitioners will deepen 

the understanding of what these alternatives can offer to a functional 

classification system that is relevant and meaningful at the national level.
49

SECTION 6. URBAN BOUNDARIES

6.1 Introduction

Many Federal transportation programs and policies rely upon a clear and welldocumented 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 censusdefined urban boundaries exclusively, or they may adjust the census-defined 

boundaries to be more consistent with transportation needs. States, in 

coordination with local planning partners, may adjust the urban area boundaries 

so fringe areas having “...residential, commercial, industrial, and/or national 

defense significance” (as noted in the December 9, 1991 Federal-Aid Policy Guide), 

are included.

Reasons for adjusting urban area boundaries for transportation planning purposes 

often relate to a need for consistency or geographic continuity. For example, it may 

be logical to include, as part of an urban area, a roadway that is used by urban 

residents but is located just outside the official Census Bureau urban area 

boundary. Or, it may make sense to designate as urban a rural pocket in the 

middle of an urban area (or to address alternating patterns of rural and urbandesignated areas). Additionally, large, low density land uses on the urban fringe 

that serve the urban population such as airports, industrial parks, regional 

shopping centers and other urban attractions may also be included in an urban 

area. 

On October 14, 2008, FHWA issued the memorandum “Updated Guidance for the 

Functional Classification of Highways” which stated, “Functional classification 

should not automatically change at the rural/urban boundary.” This extended the 

1991 Addendum to the 1989 guidance Highway Functional Classification: Concepts, 

Criteria and Procedures, which provided “greater flexibility for deciding on an 

appropriate place for changing the functional classification when rural routes cross 

an urban boundary.” The 2008 memorandum proposed further study of functional 

classification and urban area boundary adjustment which led to this document.

This section is intended to assemble and complete all previous policy given by 

FHWA for establishing urban area boundaries. It has three main objectives:

1. To provide a clear definition of adjusted urban area boundaries and other 

related boundaries

2. To define a set of technical and administrative processes by which States, 

working in conjunction with local planning partners, could develop 

adjusted urban areas based upon urban areas as defined by the US

decennial census

3. To establish data delivery protocols from the States to FHWA

The authority to 

establish the 

geographic definitions 

is set forth in Section 

101(a) of Title 23 U.S.C. 

and subsequent 

guidance has been 

provided in 23 CFR 470 

and in FHWA policy 

documents. 
Highway Functional Classification: Concepts, Criteria and Procedures

50

6.2 Defining Urban and Rural 

The terms “urban” and “rural” mean different things to different people, and in 

many cases, their definitions differ depending upon the context in which they are 

used. At their core, the concepts of urban and rural are clear; urban areas are 

considered to have dense development patterns, while rural areas are considered to 

have sparse development patterns (see Figure 6-1). What has changed over the 

years, however, is the terminology used and the technical definitions of “dense”

and “sparse”.

Figure 6-1: Prototypical Urban and Rural Areas

Urban Rural

 Source: CDM Smith

6.2.1 Census Definitions

For the 2010 Census, the Census Bureau classified as urban, all territory, 

population, and housing units located within urbanized areas (UAs) and urban 

clusters (UCs), both defined using the same criteria. The Census Bureau 

delineates UA and UC boundaries that represent densely developed territory, 

encompassing residential, commercial, and other non-residential urban land 

uses. An urban area comprises a densely settled core of census tracts and/or 

census blocks that meet minimum population density requirements, along with 

adjacent territory containing non-residential urban land uses as well as territory 

with low population density included to link outlying densely settled territory 

with the densely settled core. To qualify as an urban area, the territory identified 

according to criteria must encompass at least 2,500 people, at least 1,500 of which 

reside outside institutional group quarters.

For the 2010 Census the urban and rural classification was applied to the 50 

states, the District of Columbia, Puerto Rico, American Samoa, Guam, the 

Commonwealth of the Northern Mariana Islands, and the U.S. Virgin Islands.

For classification purposes, the Census Bureau identified two types of urban areas 

for the 2010 Census:

Urbanized Areas (UAs)—An urbanized area consists of densely developed 

territory that contains 50,000 or more people. The Census Bureau delineates UAs 

to provide a better separation of urban and rural territory, population, and 

housing in the vicinity of large places. 

Urban Clusters (UCs)—An urban cluster consists of densely developed territory 

that has at least 2,500 people but fewer than 50,000 people. The Census Bureau 

first introduced the UC concept for Census 2000 to provide a more consistent and 

The concept of 

adjusted urban areas 

has evolved since the 

issuance of the Federal 

guidance on the topic 

in Chapter 4 of 

FHWA’s Federal-Aid 

Policy issued in 

December 1991. 

According to 

definitions in 23 U.S.C. 

101(a)(33), areas of 

population greater 

than 5,000 qualify as 

urban for 

transportation 

purposes in contrast 

to the Census Bureau’s 

threshold of 2,500.
Highway Functional Classification: Concepts, Criteria and Procedures

51

accurate measure of urban population, housing, and territory throughout the 

United States, Puerto Rico, and the Island Areas.

In general, this territory consists of areas of high population density and urban 

land use resulting in a representation of the “urban footprint.” Rural consists of 

all territory, population, and housing units located outside of UAs and UCs.

Geographic entities, such as metropolitan areas, counties, minor civil divisions 

(MCDs), places, and census tracts often contain both urban and rural territory, 

population, and housing units.

6.2.2 FHWA Definitions

There are 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. A number of 

Federal agency programs use the census definitions as the starting point (if not the 

basis) for implementing and determining eligibility for a variety of their funding 

programs. 

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 Area13, while the Census 

Bureau refers to Urban Clusters. This and other differences are presented in Table 

6-1 and Table 6- 2.

Table 6-1: US Census Bureau Urban Area Types Defined by Population range

Census Bureau Area 

Definition Population Range

Urban Area 2,500+

 Urban Clusters 2,500-49,999

 Urbanized Area 50,000+

Table 6 2: FHWA Urban Area Types Defined by Population Range

FHWA Area Definition 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

Federal transportation legislation allows for the outward adjustment of Census 

Bureau defined urban boundaries (of population 5,000 and above) as the basis for 

development of adjusted urban area boundaries for transportation planning 

purposes, through the cooperative efforts of State and local officials. By Federal 

rule, these adjusted urban area boundaries must encompass the entire censusdesignated urban area (of population 5,000 and above) and are subject to 

 13 FHWA has traditionally used this term to describe Urban Areas with a population greater than 

or equal to 5,000 and less than 50,000, derived from Urban Clusters

A full description of 

the final 2010 Census 

urban area 

delineation criteria 

can be found in the 

August 24, 2011, 

Federal Register (76 

FR 53030): 

http://www.census.g

ov/geo/reference/frn

.html. 

Additional 

information 

regarding the 2010 

Census urban area 

program can be 

found: 

http://www.census.g

ov/geo/reference/ua

/urban-rural2010.html.
Highway Functional Classification: Concepts, Criteria and Procedures

52

approval by the Secretary of Transportation (23 USC 101(a) (36) - (37) and 49 USC 

5302(a) (16) - (17)). 

For the purposes of the boundary adjustment process, the term “adjusted urban 

area boundaries” refers to the FHWA boundary adjustment process in all areas of 

5,000 population and above. 

During the time between the release of the Census Bureau boundaries and the 

formal approval of the new adjusted boundaries, the previously-developed and 

approved adjusted urban area boundaries remain in effect. For FHWA and State 

DOT planning purposes, if a State DOT chooses not or is unable to adjust the 

urban area boundaries, the most recent unadjusted census boundaries will take 

effect. This could cause a roadway previously considered to be urban to now be 

considered rural, which may affect Federal aid funding eligibility. 

To avoid this situation, States are encouraged to work with their FHWA Division 

Office and their local planning partners to go through the process of developing 

the adjusted urban area boundaries within the recommended timeframe.

6.3 Relationship to Functional Classification

While the urban/rural designation is independent of the functional classification, 

it is important to recognize that the adjusted urban area boundary is a significant 

factor in developing the functional classification of a road in an urban/rural 

context. 

Recent changes to FHWA policy have normalized14 the concepts of urban 

boundaries and functional classification to improve consistency. The seven 

functional classifications each for urban and rural areas create 14 possible 

combinations of functional class and area type. As an example, a roadway 

classified as a Minor Arterial that happens to be in an urban area has a combined 

classification of Urban Minor Arterial. There is no change in the definitions of the 

functionally classified roads; nor does this in any way change the eligibility of rural 

and urban-classified roads for Federal programs and policies, or how highway 

statistics are reported. 

This change in policy provides an opportunity to clarify how functional 

classifications at the boundaries of urban/rural areas should be treated. The 

previous practice in some States of automatically changing the functional 

classification of a route that crosses into or out of an adjusted urban area boundary 

can be phased out and eliminated. Upgrading due to an actual change in function 

should be the operative criterion.

Special attention should be paid to locations at which roadways and boundaries 

are in close proximity. The adjusted urban area boundary should be designed to 

eliminate or minimize a roadway’s snaking in and out of the boundary. In these 

cases, as the boundary is adjusted, it needs to be clearly defined that the road is 

either in or out. This adjustment serves to maintain consistent designation of 

these peripheral routes and avoids the situation of a roadway alternating between 

urban and rural designations. Special care should be taken when developing the 

 14 Normalization here means simplifying the functional classification so that a roadway is 

classified with one meaning while urban/rural is a separate context in which the road is located.
Highway Functional Classification: Concepts, Criteria and Procedures

53

boundary so that spatial consistency is maintained with the roadways and 

associated attributes.

Roads that define a boundary should be considered consistently urban or rural, 

and it is strongly recommended that these roadways be carefully evaluated before 

they are included in or out of the adjusted urban area boundary. For example, in 

Figure 6-2, Plympton Street (a Major Collector) defines the adjusted urban area 

boundary and is considered to be an Urban Major Collector, while Plymouth Street

(a Local Road) is considered to be an Urban Local Road.

Figure 6-2: Example of Roadway Coinciding with Adjusted Urban Area

Source: CDM Smith 2012; Data provided by Massachusetts DOT

6.4 Developing Adjusted Urban Area Boundaries

This section outlines a series of recommended technical and procedural steps to 

develop adjusted urban area boundaries. These tasks are typically conducted 

through a collaborative effort between State DOTs and local planning partners. 

The process begins with the release of the urban area boundaries by the Census 

Bureau and concludes with the approval of the appropriate FHWA Division Office. 

Overall, the process typically takes between six months and a year to complete 

from the time that the census boundaries are released.

As described previously, there is no requirement to adjust the census urban 

boundaries. States may adopt the census boundaries as is, or they may adjust them 

for transportation planning purposes. The only official requirement is that an 

adjusted boundary includes the original urban area boundary defined by the 

Census Bureau in its entirety. In other words, any adjustment must expand, not 

contract, the Census Bureau urban area boundary.

6.4.1 Adjusted Urban Area Boundaries – Technical Tasks

The first step in defining adjusted urban area boundaries is to obtain the census 

urban area geospatial boundary files from the Census Bureau. These files are 

available from FHWA’s HEPGIS website www.hepgis.fhwa.dot.gov or from the 

Census Bureau in a variety of GIS-compatible formats, including Arc/Info export, 

Arc View shape file and Arc/Info format. Historical cartographic boundary files 

from previous censuses are available for download at: 
Highway Functional Classification: Concepts, Criteria and Procedures

54

www.census.gov/geo/www/cob/bdy_files.html.

These urban area boundary files should be edited in GIS. Additional GIS layers 

should also be gathered from the same year as the decennial census (e.g., 2010) or 

of similar vintage (see Figure 6-3). Potentially useful GIS layers include:

 Land use, including areas of recent growth

 Roadway network

 Railroads

 Transit routes

 Ports (e.g., airports, seaports)

 Military installations

 Other significant traffic generators

 Hydrography

 Municipal boundaries (i.e., incorporated areas)

 Digital ortho-photography

Figure 6-3: 2000 Census Urban Cluster and Urbanized Areas (Ohio and Vicinity)

Source: 2000 US Census

6.4.2 Consideration Factors for Adjusting Urban Areas

When adjusting the urban areas, a variety of factors should be considered. The list 

below describes these factors and includes an example for each. All examples are 

courtesy of the Arizona or Massachusetts departments of transportation. 

 The adjusted urban area boundary will encompass the entire urban area (of 

population 5,000 or greater) as designated by the Census Bureau. In Figure 

6-4, no part of the original urban area was removed.
Highway Functional Classification: Concepts, Criteria and Procedures

55

Figure 6-4: Example Original Urban Area

Source: Arizona DOT; http://azdot.gov/mpd/gis/fclass/urban.asp

 The adjusted urban area boundary will be one, single contiguous area. In 

Figure 6-5, the new boundary, like the original census boundary, is a single 

contiguous area without any holes or discontinuities, such that there is no 

rural area contained within the outer urban boundary.

Figure 6-5: Example Single Contiguous Area

Source: Arizona DOT; http://azdot.gov/mpd/gis/fclass/urban.asp

 The adjusted urban area boundary often is designed to encompass areas 

outside of municipal boundaries that have urban characteristics with 

residential, commercial, industrial or national defense land uses that are 

consistent with or related to the development patterns with the boundary.

The adjusted urban area boundary should include terminals and their access 

roads, if such terminals lie within a reasonable distance of the urban area 

(e.g. airports, seaports). In Figure 6-6, the urban area was expanded to cover 

the nearby Air Force base.
Highway Functional Classification: Concepts, Criteria and Procedures

56

Figure 6-6: Example Area Expanded to Cover Air Force Base

Source: Map created by CDM Smith, using data provided by Massachusetts DOT and US 2000 

Census.

 The adjusted urban area boundary is adjusted in many instances to

encompass all large traffic generators that are within a reasonable distance 

from the urban area (e.g., fringe area public parks, large places of assembly, 

large industrial plants, etc.). In Figure 6-7, the urban area was expanded to 

include the industrial area east of the census urban area boundary.

Figure 6-7: Example Area Expanded to Include Industrial Area

Source: Arizona DOT; http://azdot.gov/mpd/gis/fclass/urban.asp with overlay graphic by CDM 

Smith to identify industrial plant.

 The adjusted urban area boundary should consider transit service routes 

(e.g., bus route, passenger rail line) in the placement of a boundary location. 

However, their inclusion should not unduly distort the shape or composition 

of the original census-defined urban area boundary. 

 The adjusted urban area boundary should be defined so that its physical 

location is easy to discern in the field from data shown on the map. 

Whenever possible, if the boundary is going to deviate from political 

jurisdictional boundaries, it should follow physical features (e.g., rivers, 

streams, irrigation canals, transmission lines, railroads, streets or highways). 

In instances where physical features are lacking, the boundary should cross at 
Highway Functional Classification: Concepts, Criteria and Procedures

57

roadway intersections which are readily identifiable in the field. In Figure 

6-8, the boundary was adjusted to align with the major east-west roadway to 

the south.

Figure 6-8: Example Boundary Adjusted to Align with Major Roadway

Source: Source: Arizona DOT; http://azdot.gov/mpd/gis/fclass/urban.asp

 After the adjusted urban area boundary has been defined using all the factors 

previously listed, remaining boundary irregularities should be minimized to 

avoid the confusion that irregular boundaries can create. In Figure 6-9, the 

boundary was adjusted to be considerably less complex than the original 

irregular census boundary.

Figure 6-9: Example Boundary Adjusted for Simplicity



Source: Arizona DOT; http://azdot.gov/mpd/gis/fclass/urban.asp
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58

Additional recommendations regarding the adjustment of the urban area 

boundaries include:

 Adjusted urban area boundaries should be defined so that confusion or 

ambiguity is minimized. For example, a boundary should not be drawn in the 

middle of a divided highway. The divided highway should be either 

completely in or completely out of the urban area boundary.

 In instances where a roadway defines the boundary between two urban areas, 

the roadway should be clearly assigned to the urban area it primarily serves. 

If the roadway serves each urban area equally, a business rule should be 

developed that assigns the roadway appropriately. 

 If access controlled roadways are used to define the adjusted urban area 

boundary, all ramps and interchanges should be either included or excluded 

concerning the adjusted urban area boundary and interchanges should not be 

divided by the boundary.

 For coastal areas, if the intent of the adjusted urban area boundaries is to be 

reflective of the shoreline, then the generally accepted coastal boundaries 

most commonly used for geospatial processes, such as spatial analysis or 

map-making, should be used.

6.5 Adjusted Urban Area Boundaries – Procedural 

Tasks

If States and their local partners choose to adjust the urban area boundaries, then 

they must be reviewed, at a minimum, in conjunction with the census urban area 

boundary release.

15 FHWA recommends that this process be completed within 1

year of the release of the census urban area GIS datasets. FHWA considers a State’s

DOT, working with the appropriate local government entities, to be the authority 

during this process and relies upon State DOTs to take an active leadership role.

6.5.1 Risk Factors to Urban Area Adjustment Schedule

There are several risk factors that could potentially arise and impact the amount of 

time it takes to complete the adjustment process. Therefore each State should

develop a carefully planned approach for addressing these potential risk factors, 

which include:

 A large number of urban areas within a State

 Newly created urban areas

 Merging of previously separate urban areas

 Urban areas that cross State boundaries

 A large number of local planning partners with which to coordinate

 Inconsistency in the application of adjustment criteria across the State

 Inconsistent interim data submittal formats

 Lack of active engagement by local planning partners

 15 Although there is no specific FHWA policy on how often adjustments to urban area boundaries 

can be made, states are encouraged to make such adjustments as infrequently as possible and 

only when deemed absolutely necessary. 
Highway Functional Classification: Concepts, Criteria and Procedures

59

 Lack of DOT resources to complete the process in a timely fashion

6.5.2 Urban Area Adjustment Schedule

FHWA Division Offices will correspond with State DOTs to launch the effort of 

developing the adjusted urban area boundaries. This transmittal is expected to be 

delivered soon after the Census Bureau releases its urban area boundaries, which 

typically occurs about 12 to 18 months following the decennial census. FHWA’s 

transmittal will remind the State DOTs of their responsibilities; include 

notification of the availability of the Census Bureau’s urban area boundary files;

and provide information regarding how and when the updated boundary data 

should be submitted.

Figure 6-10 and the list that follows present a good practice level of 

procedural steps that should be completed within 12 months of the release 

of the Census Bureau’s urban area boundary files.

Figure 6-10: Good Practice Level of Procedural Steps for an Urban Boundary Update Process

1. Mobilize the Urban Area Boundary Adjustment Process

a. Acquire newly developed urban area boundaries from US

Census. Obtain the latest decennial census urban area boundaries 

from the Census Bureau.

b. Form a team to guide the urban area boundary update 

process. Staff the team with FHWA Division personnel, along with 

State and regional transportation planners who have a vested 

interest in the final delineation of the boundaries. Individuals with 

experience in functional classification, Federal transportation 

funding, highway design, traffic operations and the metropolitan 

1 2 3 4 5 6 7 8 9 10 11 12

1a. Obtain Urban Area Boundaries from U.S. Census

1b. Establish AUAB Review Team

1c. Generate data, maps, etc. for use by local planning partners

1d. Contact local planning partners

2a. Deliver data and documents to local planning partners

2b. Work with Local Planning Partners in Adjusted Urban Area Boundary Review Process

3a. Gather, review, and incorporate all proposed changes

3b. Submit draft Adjusted Urban Area Boundary information to FHWA

3c. Incorporate Adjusted Urban Area Boundary Changes into Enterprise Systems 

Month

1. Mobilize the Adjusted Urban Area Boundary Update Process

2. Work with Local Planning Partners in Adjusted Urban Area Boundary Review Process

3. Make Adjusted Urban Area Boundary Changes
Highway Functional Classification: Concepts, Criteria and Procedures

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transportation planning process should have a role in this process. 

This review team should be responsible for reviewing draft 

adjusted urban area boundary submittals from local planning 

partners.

c. Generate data, maps, etc. for use by local planning partners.

Incorporate urban area boundaries from the census into data and 

maps that that are relevant to local planning partners. These may 

include statewide, district, county and municipal scales.

d. Contact local planning partners. Contact the impacted local 

planning partners to explain the task at hand and request their 

participation. For Urbanized Areas contained and/or very 

proximate to metropolitan planning areas, the MPO should be a 

key partner. For Urban Clusters, regional planning agencies, 

counties and/or local municipalities should be consulted. 

However, for many of these urban areas, additional effort may be 

required to properly engage these partners. In these instances, it is 

appropriate for State DOTs to make urban area adjustments in 

these areas. Finally, in some instances, regional transit service 

providers should also be consulted to understand their short-term 

routing plans.

2. Work with Local Planning Partners in the Adjusted Urban Area 

Boundary Update Process 

a. Deliver data and documents to local planning partners. Share 

the original decennial census-based urban boundary maps and/or 

GIS data (including both Urbanized Areas and Small Urban Areas) 

with the local planning partners. In addition, to inform the 

partners and the process more completely, it helps if maps and/or 

GIS data representing both the previous unadjusted and adjusted 

urban area boundary are shared in a timely manner. This 

transmittal should include specific instructions in terms of data 

formats, spatial accuracy, update processes and expected 

completion dates, as well as this guidance document. In-person or 

video conference meetings are encouraged to enhance

communication and mutual understanding. Creation of adjusted 

urban area boundaries should follow each State’s GIS data editing 

and quality control procedures (e.g., issues of scale) and performed 

by qualified GIS users. 

b. Work with local planning partners. As necessary, each State 

DOT will need to work with the local planning partners to ensure 

that the urban area adjustment process is meeting their 

expectations. Close collaboration with MPOs is extremely 

important, and regional workshops hosted by MPOs can be very 

valuable in ensuring there is a common understanding of the 

process and schedule. While the exact details surrounding 

information exchange may vary from state to state, the expectation 

is that local planning partners will review the US census urban area 

boundaries in the context of the existing adjusted urban area 

boundaries (based upon the previous census) and determine the 
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61

extent to which the boundaries should be adjusted for 

transportation planning purposes. The local planning partners 

should submit a set of proposed adjustments to the current US

Census urban area boundaries in their area to their State DOT.

3. Make Adjusted Urban Area Boundary Changes

a. Gather, review and incorporate proposed changes from local 

planning partners. As local planning partners submit their 

recommendations for adjusted urban area boundaries, the State 

DOT must review the proposed adjustments to ensure that they 

are reasonable. At the very least, the DOT must ensure that no 

territory considered urban by the Census Bureau be left out of the 

adjusted urban area boundary. In addition, the State DOT should 

review all proposed adjusted urban area boundaries paying 

particular attention to locations where the adjusted urban area 

boundaries are co-located with another feature such as a roadway, 

a municipal boundary or a hydrographic feature. Some follow-up 

meetings may be necessary to resolve issues discovered by the 

DOT. The updated GIS adjusted urban area boundaries need to be 

incorporated into the master urban boundary layer and subjected 

to the DOT’s GIS quality control checks with the metadata for the 

layer updated.

b. Submit draft adjusted urban area boundary information to 

FHWA Division Office. Once the State DOT has successfully 

reviewed and concurred with all recommend adjusted urban area 

boundaries, the State DOT should submit the draft final adjusted 

urban area boundaries to its FHWA Division Office for final 

approval. The specific format of data delivery should be worked 

out between the State DOT and their FHWA Division Office. 

Various geospatial formats will be acceptable, and as developed, 

FHWA systems such as HPMS or HEPGIS may be used. As a final 

resort, hard copy maps at a scale sufficient to identify the adjusted 

urban area boundaries can be submitted. 

c. Incorporate adjusted urban area boundary changes into 

Enterprise Systems. Once FHWA has approved the adjusted 

urban areas, the State DOT should incorporate the adjusted urban 

area boundary changes into the enterprise geospatial database 

systems that house the official record of the adjusted urban area 

boundaries. States are required to submit their adjusted urban area 

boundaries to FHWA when changes are made to the boundaries. 

In most cases, this submittal should only occur once after the State 

has completed its adjustment process. 
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Table 6-3 presents key milestones for the overall development and submittal 

process (for example, using submitted data based upon the 2010 US Census data.

Table 6-2: Key Milestones for Development and 

Submittal of Adjusted Urban Area Boundaries

Event

Months Following Decennial Census 

Data Release (CDR)

Census releases urban area boundaries 

and FHWA issues transmittal letter Month 24

Begin adjusted urban area boundary 

update process Month 24

DOT works with planning partners to 

define adjusted urban area boundaries Month 27-Month 33

Provide draft final data and/or maps to 

FHWA Division Office for review Month 34

DOT incorporates updates Month 35

DOT submits adjusted urban area 

boundaries via annual HPMS submittal Month 36

Each State should submit only boundaries for the HPMS submittal that have been 

approved by their FHWA Division Office. 

Table 6-4 lists the attributes that are required within the FHWA geospatial 

database.

Table 6-3: Geospatial Database Required Attributes

Field Name Description

Year_Record Year for which the data apply

Urban_Code Census urban code

Urban_Name Urban name

Census_Pop Census population (“recalculated” based upon the 

adjusted urban area boundary)

Census_Land_Area Census land area (in square miles)

Shape Polygon feature

6.6 Adjusted Urban Area Boundaries – Data 

Transmittal Process

Each State DOT should coordinate with its local FHWA Division Office to discuss 

the data transmittal process. To the extent possible, all draft final boundaries 

should be submitted electronically in the form of GIS data and/or PDF maps. If 

GIS data are provided, appropriate metadata delineating the spatial accuracy, 

projection and definition/domain of all attributes should also be provided, as well 

as supporting documentation that briefly describes the process by which the 

boundaries were adjusted. In addition, each adjusted urban area boundary should 

be a single (multi-part, if necessary) polygon GIS feature. Feature names and codes 

should follow Federal Information Processing Standards (FIPS) conventions as 

well as any applicable State naming and coding standards.
63

SECTION 7. GRAPHICS SOURCES

Akos Szoboszlay

Arizona DOT

CDM Smith

Creative Commons Attribution-Share Alike 2.0 generic license; Benjamin 

Clark

Department for Transport, United Kingdom 

FHWA

Google Earth Pro

Lund University, Department of Technology and Society 

Idaho DOT

Institute of Transportation Engineers

Idaho DOT

Massachusetts DOT

Minnesota DOT

Ohio DOT

Ohio Statewide Imagery Program

Oregon DOT

Smart Transportation Guidebook

Texas DOT

US Census (2000)
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