The document discusses the functional classification of roads. It defines mobility as the ability to move goods and passengers to their destination in a reasonable time, and accessibility as the ability to reach a desired destination. It then explains that the first step in the design process is to define the function of the road based on the anticipated traffic volume and composition. The functional classification determines the appropriate design speed and geometric criteria. Arterials provide the highest level of mobility with some access control, collectors provide less mobility and balance access and mobility, and local roads focus on access with little through movement.

1. Functional Classification of Roads
Mobility & Accessibility
Mobility: The ability to move goods and
passengers to their destination. (in a
reasonable time)
Accessibility: the ability to reach
desired destination,
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2. • 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. 2
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3. LOS A
LOS C
LOS B
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4. LOS D
LOS F
LOS E
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5. • Basic Classification of Highways
Arterials
Higher degrees of Mobility
Low degree of access
Collectors
Balance between Arterials and Collectors
Locals
Lower degrees of mobility
High degree of access
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6. Functional
System
Services Provided
Arterial Provides the highest level of service at the
greatest speed for the longest uninterrupted
distance, with some degree of access control.
Collector Provides a less highly developed level of service
at a lower speed for shorter distances by
collecting traffic from local roads and
connecting them with arterials.
Local Consists of all roads not defined as arterials or
collectors; primarily provides access to land
with little or no through movement.
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7. ¨ Principal arterial - main movement
(high mobility, limited access)
¨ Minor arterial - interconnects principal
arterials (moderate mobility, limited access)
¨ Collectors - connects local roads to arterials
(moderate mobility, moderate access)
¨ Local roads and streets - permits access to
abutting land (high access, limited mobility)
State Design Standards – Highway Design Manual
e.g. Texas
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8. Role of Functional Classification in Design Process
Functional
Classification
Design Speed
Cross Section
Horizontal/Vertical
Alignment
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9. Functional
Classification
20 mph 30 mph 40 mph 50 mph 60 mph 70 mph
Rural Principal
Arterial
X X X
Rural Minor
Arterial
X X X
Rural Collector X X X
Rural Local Road X X X
Roadway Design Manual, Virginia DOT
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NHA is custodian of 39 national highways /
motorways / expressway / strategic routes
having a total length of 12,131 kms.
It is 4.6% of total national road network i.e.
263,775 kms, however, it carries 80% of
commercial traffic.
N-5 which is blood-line of Pakistan, carries
65% of this load in the country.

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