defination of intersection and also different types of intersection with diagrams and also it consists of advantages and dis advantages of at grade intersection and grade separate intersection and also planning considerations and need of construction of intersection. it also consists of case study of chennai.
2. Contents
What is an intersection
Types of intersection
Grade separate intersection
At grade intersection
Traffic operation
Principles considered for design
Advantages and limitations
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3. What is an intersection
► Area where two or more roads meet or cross
each other.
► Area for vehicles to turn to different
directions.
►vehicles moving in different directions want to
occupy same space in same time Hazardous
locations.
► Intersection is a point of large number of
major conflicts.
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4. Need of intersection design
Intersection is a point of large number of major conflicts.
Good intersection design aims at
Minimization of the magnitude and characteristics of the
conflicts.
A simplification of driver route selection process.
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5. Planning consideration for interchange
Land availability
Interchange spacing
Access control
Land use
Warrants
design consideration
safety
congestion
traffic volume
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6. TYPES OF INTERSECTION
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Grade separated
intersection
At-grade
intersection
• It is also called
interchanges.
• Roads at different
elevations
• Connected by ramps
Roads at same
elevation
8. Grade separated intersection
It is a bridge that eliminates crossing conflicts at intersections
by vertical separation of roadways in space.
Route transfer at grade separation is accommodated by
interchange facilities consisting of ramps.
The interchange configuration are designed in such a way to
accommodate economically the traffic requirements of flow
operation on the crossing facilities, physical requirements of
the topography, adjoining land use, right-of-way and
direction of movements.
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10. Underpass
An underpass or tunnel is an
underground passageway,
completely enclosed except for
openings for ingress and egress,
commonly each end.
A tunnel may be for foot or
vehicular road traffic, for rail traffic.
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11. Overpass
An overpass also know as a flyover,
is a bridge, road, railway or similar
structure that crosses over another
road or railway.
A pedestrian overpass allows
pedestrians safe crossing over busy
roads without impacting traffic.
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12. Trumpet interchange
Trumpet interchanges have been used where one
highway terminates at another highway.
These involve at least one loop ramp connecting
traffic either entering or leaving the terminating
expressway.
The principal advantages are low construction cost
and are useful for highways.
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14. Diamond interchange
Simplest form of grade separated
interchange between two roadways.
The conflicts between through and
crossing traffic are eliminated by a bridge.
Diamond interchange are most effective in
area where traffic is light.
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16. Cloverleaf interchange
Eliminates all crossing
movements conflicts by use of
weaving sections.
It replace a crossing conflicts
with a merging, followed some
distance farther by a diverging
conflicts.
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18. Partial cloverleaf interchange
Partial clover leaf is a modification
that combines some elements of a
diamond interchange with one are
more loops of a cloverleaf to
eliminate only the more critical
turning conflicts.
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20. Directional interchange
A directional interchange provides
direct paths for turning movement .
These interchanges contain ramps for
one or more direct or semi direct left
turning movements.
.
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22. At grade intersections
► At-grade intersections in which all the exchanges between the
roads take
place on the same plane.
These are:
all paved / un-channelized intersection
Channelized intersection
Roundabout
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23. Types of at grade intersection
All paved / un-channelized intersection
1. No restriction to vehicles
2. Can use any part of intersection area
3.they can be cross, t type, multileg
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27. Traffic operation
Diverging: vehicles moving in one direction is
separated into different streams according to
their destination.
Merging : process of joining the traffic coming
from different approaches and going to a
common destination into a single stream.
Weaving: combined movement merging and
diverging movements.
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30. Kathipara
Kathipara is an important road
junction in Chennai, India
It is located at the intersection of
the Grand Southern Trunk
Road, Inner Ring road.
Kathipara flyover is the
largest cloverleaf flyover in South Asia.
A cloverleaf grade separator was
constructed as part of the NHDP to
ease traffic congestion at the junction.
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31. Advantages
Grade separator provides maximum facility to the
crossing traffic and avoids the accident while crossing.
They provide increased safety for turning traffic. By
introducing indirect interchange ramp, even right turn
movements can be made quite easy and safe
Grade separation is an essential part of controlled access
highway like an expressway.
Traffic capacity is increased.
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32. Limitations
All the vehicles are forced to slow down so the cumulative
delay will be much higher than channelized intersection.
Even when there is relatively low traffic, the vehicles are
forced to reduce their speed.
Require large area of relatively flat land costly at urban areas.
The vehicles do not usually stop at a rotary so not suitable
when there is high pedestrian movements.
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33. Reference
Google
IRC 92- 1985 AND IRC92-2017 (GUIDELINES FOR THE
DESIGN OF INTERCHANGES IN URBAN AREA)
YouTube
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