Roads and Streets
o h n
Director, Highway Traffic Safety Center
University of Illinois, Urbana-Champaign
The highway transportation network in the State of Indiana, like
that in any other state or country, consists of a conglomerate of roads,
streets, highways, paths, alleys, and freeways. The mileage of each
type of facility as well as the service provided by and the use made
of each section of roadway varies from region to region as well as
within any particular region.
The situation is complicated by various layers of administrative
responsibility of differing management, legal, technical and fiscal abili
ties and resources.
Conditions are further compounded by the fact that the number of
drivers and vehicles utilizing various highway facilities is increasing
at a much higher rate than the improvement of the facilities them
selves. For example, in 1969 Americans traveled slightly more than
one trillion vehicle miles and it is estimated that the amount of yearly
travel will increase from 14 to 24 percent within the next five-year
period. This rapid growth can easily be compared with the seemingly
deliberate capability for improving our highway transport system.
Thus, it is imperative that all levels of government be able to
cooperatively develop, operate, and maintain a comprehensive highway
transportation network wrhich is capable of accommodating motor
vehicle travel in an efficient, safe, and economical manner.
CONCEPTS OF ROAD CLASSIFICATION
An essential component of effective highway management is the
classification of roads and streets. This classification may be on such
widely divergent bases as traffic volumes, administrative responsibility,
method of financing, or design characteristics.
The functions of any roadway are twofold and often in opposition
to each other. First, the roadway should provide for the safe and
expeditious through movement of persons and goods (mobility).
Second, it must provide accessability to abutting property (land access).
Obviously, the conflict which exists between effectively serving
through traffic movements and yet providing access to a wide variety of
land uses necessitates diverse types of roadways. This difference in
the character of service provided by a given roadway, or its function,
is the basis for a classification procedure known as functional
Fundamental to this procedure is the knowledge that travel re
quirements are not independently served by individual roads and
streets but by a network of roadways. Functional classification is used
to determine how this travel can be logically and efficiently channelized
along the various individual components within the roadway network.
FUNCTIONAL CLASSIFICATION IN INDIANA
Through the mandate of 1968 Federal legislation and 1969 In
diana legislation, all Indiana highway officials are required to imple
ment two parallel programs for classifying all streets, roads, and high
ways within the state. Because these two programs have similar
objectives, a thorough approach will satisfy the requirements of both
Procedures have been developed to assure the uniform functional
classification of all roadways within the state and nation. This activity
is being coordinated through each of the State Highway District offices.
ELEMENTS OF FUNCTIONAL CLASSIFICATION
The concentration of traffic on a limited mileage of arterial road
ways is a basic goal of functional classification. Therefore, the proper
“function” of any roadway is determined by consideration of numer
ous complex factors which help to identify the relative importance of
each segment in the total road network.
Consideration is given to a roadway section’s contribution to traffic
mobility, land access, and the general social, economic, and cultural
welfare of the public. Three basic types of roads and streets are
identified in the functional classification process: arterials, collectors,
The classification of a given roadway into one of these three
groups involves the determination of the level or type of service that
the road is expected to provide. Certain specific factors must be
evaluated before the classification of a road can be established. These
1. Length of trips traveled on the road;
2. Speed of operation;
3. Directness of routing;
4. Degree of access control;
5. Degree of land service;
6. Freedom of movement;
7. Service to activity centers or traffic generators;
8. System continuity;
9. Traffic volume; and
10. Route spacing.
Characteristics which are attributable to arterial, collector, and local
routes relate to these ten specific factors.
For example, arterials are expected to provide direct routings for
large volumes of traffic traveling long distances at high operating
speeds. Collector roads serve a dual function: they provide some
degree of mobility and they also serve abutting property while servic
ing shorter trips and acting as feeders to the arterials. The roads in
the local system provide direct access to abutting property for relatively
short trips and low volumes at the expense of free-flowing movement.
W HAT HAPPENS AFTER FUNCTIONAL
After all of a state’s roadway mileage has been functionally classi
fied, it is then necessary to determine the administrative responsibilities
of the state, counties, and cities for the resulting road classifications.
Joint discussions and hearings are held to obtain agreement on
highway classifications within individual jurisdictions. One of the
most controversial points is always the transferring of responsibility for
existing roads from one jurisdiction to another.
In Illinois, for example, the Highway Study Commission recom
mended the following changes in current mileage responsibilities:
In order to assist local jurisdictions to properly undertake their
new responsibilities under the reclassified systems, the Study Com
mission recommended modifications in user imposts and their allocation
among the various governmental jurisdictions.
The Commission also recommended the following annual mileage
allowances for a five year period for transfers from the State system
to local jurisdictions:
1. $2,500 per mile for transfers to cities and urban counties
(counties with populations of 180,000 persons or more accord
ing to the 1960 U.S. Census) ;
2. $2,000 per mile for transfers to other counties;
3. $1,000 per mile for transfers to townships and road districts;
It was estimated that the mileage transferred from the State system
would be 900 miles to cities, 925 miles to urban counties, 2,385 miles
to other counties, and 700 miles to townships. Total costs over the
five year period were expected to be approximately $52 million.
The Illinois legislature has not acted on these recommendations of
the Highway Study Commission concerning functional classification.
Another problem which faces the different governmental units is
the case where an existing road will be reclassified to a lower system
as soon as a new roadway is developed. In their interim period, which
governmental unit should be responsible for the existing roadway?
For example, suppose an existing rural state highway now classi
fied as an arterial, will be paralleled by a programmed freeway de
velopment. When completed, the freeway will then become the arterial
and the existing route reclassified as a collector. If the state has
responsibility for arterials and the county has responsibility for col
lectors, should the state or the county be responsible for the old road
while the freeway is being built?
Problems such as these clearly indicate the necessity for close
cooperation and continuous, full participation in functional classification
by all units of government.
BENEFITS DERIVED FROM FUNCTIONAL
In general, the development of integrated state, county, and city
roadway systems provides state and local legislators, highway adminis
trators, engineers, and planners with a firm foundation for:
1. The establishment of administratively practical highway systems;
2. The designation of minimum design and safety standards for
each of the functional highway systems;
3. A logical and orderly basis for determining and evaluating
present and future highway needs and improvement priorities;
Stated another way, the functional classification of streets, roads
and highways produces several administrative advantages:
1. It allows consistency of planning, design and operation for
similar types of facilities;
2. It allows units of government more efficiently and economi
cally to provide for construction, maintenance and traffic opera
tion because responsibilities are limited to particular classes of
3. It allows more uniform assignment of responsibilities to the
same type of governmental unit; and
4. It prevents inefficient “skip” maintenance and operation.
All of the basic premises of functional classification—the “level of
service” concept—the trip length—and the extent of access control are
designed to accomplish one result, the most efficient total highway
network. In other words, functional classification is intended to result
in the “highest and best” use of highway funds.
Functional roadway system classification is not a static plan. It
provides an orderly basis for the gradual reallocation of roadway re
sponsibility among the various governmental units. It must be applied
to existing and proposed routes.
When combined with highway needs determinations and fiscal
plans, present and future functional classification of roadway enables
the development and implementation of the most desirable highway
policies by all levels of government.
“Developing and Analyzing Functionally Classified Networks
Utilizing Traffic Simulation—Phase I,” Highway Planning Technical
Roads, Washington, D. C., February 1966.
“1968 National Highway Functional Classification Study Manual,”
U. S. Department of Transportation, Federal Highway Administra
tion, Bureau of Public Roads, Washington, D. C., April 1969.