This document discusses the classification and components of highways. It covers: 1) Static characteristics like lane widths and vertical clearances that affect highway design. 2) Kinematic characteristics like acceleration and passing maneuvers that influence design elements. 3) Functional classification of highways as arterial, collector, or local roads based on their balance of mobility versus accessibility. 4) Distinctions between freeways and expressways based on access control. 5) Components of highway cross-sections including lanes, medians, shoulders, ditches, and slopes.

1. Geometric Design
University of Jordan

2. 2
Static Characteristics
• Size:
• Design of lane widths, parking bays, etc…
• Vertical clearance
• Weight:
• Pavement design, bridge design, axle loads
• Maximum grade
• Radius of Curvature:
• Intersection design
• Interchange ramps

3. 3
Kinematic (Dynamic) Characteristics
• Acceleration (Constant or variable):
• Passing maneuvers
• Gap acceptance
• Dimensions of freeway ramps and passing lanes
• Motion elements (Distance and Velocity)

4. 4
Functional classification of highways
• Highways are classified either by
– The function they serve (functional classification)
– The entity responsible for their construction and
maintenance (jurisdictional classification)
• Two concepts are used when classifying highway by
their function
– Mobility: continuous travel
– Accessibility: direct access to abutting (next to or adjacent)
property
• Some roads serve one of these two function while
few can satisfy both

5. 5
Mobility
Accessibility
Function
classification

6. 6
Mobility vs. Accessibility

7. 7
Mobility versus accessibility

8. 8
Three Major Roadway Classes and their
functions:
• Arterial (high mobility, low access, long trips,
fast speeds)
• Collector (moderate, moderate, moderate,
moderate)
• Local (low, high, short, slow)

9. 9
Roadway Functional Classes
• Determined by characteristics:
– Function
– access density
– traffic demands
– trip length
– expected speed

10. 10

11. 11
Freeway versus expressway
• The distinction between freeways and expressway is
based on the accessibility control
– Freeways have a full control of access [access or exit are
permitted only at controlled locations (exit ramp)]
– Expressways have a partial access control. (access or exit
are maybe permitted directly from or adjacent land or via
a limited number of at grade intersections)

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Rural road classification
Principal Arterials
• Function: Long disance Travel and Connect
urbanized areas
• Characteristics: Long trips, no stubs, high
speed, widely spaced, full/partial access
control
• Subclasses: Freeways, Other non-Freeways
with access control

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Minor Arterials
• Function: connect small urban areas with
major trip generators
• Characteristics: Moderate everything
(routes, speed, spacing, mostly mobility)

14. 14
Rural Collectors
• Major Collectors: Connect small twon to large towns not
served by arterials, link entities with nearby arterials, urban
areas
• Minor Collectors: Serve remaining small towns, link local
traffic generators with rural areas
• Characteristics: Shorter, Moderate Speeds (in rural areas),
Intermediate spacing

15. 15
Rural Local Roads
• Function: Provide access to land on collector
network, serve short distance travel
• Characteristics: Short routes that terminate at higher
classes, relatively low speeds, intermediate spacing

16. 16
Urban Functional System
Principal Arterials
• Functions: carry most trips entering/leaving urban
area, serve intra-urban trips, carry intra-urban and
intercity bus routes, provide continuity to rural
arterials
• Characteristics: longest distance routes and
highest volume, high speed, spacing is less than 1
km in CBD and greater than 8 km in urban fringe,
full/partial access control
• Subclasses: interstates, other freeways and
expressways, other principal arterials with partial
access control

17. 17
Urban Minor Arterials
• Functions: interconnect with and augment
principle arterials, accommodate moderate
length trips, distribute traffic, carry local buses,
provide intra-community continuity, connect to
urban collectors
• Characteristics: moderate trip length high
volumes, moderate speeds, spacing 0.2 to1.0 km
in CBD and 3 to 5 km in suburbs

18. 18
Urban Collectors
• Functions: Provide traffic circulation within
residential neighborhoods and industrial/commercial
areas, Collect traffic from locals and channel to
arterials, Carry local buses, Provide some direct land
access
• Characteristics: Shorter than minor arterials,
Moderate speeds, Spacing intermediate to arterials,
Penetrates residential neighborhoods
• Subclasses: major and minor

19. 19
Urban Locals
• Functions: Provide direct access to land,
Connect properties to higher class streets (i.e.,
collectors)
• Characteristics: Short in length, Dead end –
terminate at collections, Low speeds, No bus
routes

20. 20

21. 21
Highway
Components
Cross-section

22. 22
Cross section components
• Highways are categorized into
– Divided highways
– Undivided highways
• The distinction is based on the viability of median (Divided highways).
• The components of divided highways within the right of way are
– Carriageway or travelling lanes
– Median
– Shoulder
– Ditches
– Side-slopes
– Barrier
– Marking
– Cross section slope