INTERSECTIONS

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.

1. PRESENTED BY : V. HEMALATHA (NM2104TE03) 1 1 Intersection

2. Contents What is an intersection Types of intersection Grade separate intersection At grade intersection Traffic operation Principles considered for design Advantages and limitations 2

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 . 3

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 . 4

5. Planning consideration for interchange Land availability Interchange spacing Access control Land use Warrants design consideration safety congestion traffic volume 5

6. TYPES OF INTERSECTION 6 Grade separated intersection At-grade intersection It is also called interchanges. Roads at different elevations Connected by ramps Roads at same elevation

7. GRADE SEPARATED INTERSECTION 7 Grade separated intersection

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 . 8

9. Types of grade separate interchanges Underpass Overpass Trumpet interchange Diamond interchange Cloverleaf interchange Partial Cloverleaf interchange Directional interchange 9

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 . 10

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 . 11

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 . 12

13. Trumpet interchange 13

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 . 14

15. Diamond interchange 15

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. 16

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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 . 18

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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 . . 20

21. 21 At grade intersection

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 22

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 23

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25. Channelized intersection 1.Traffic islands are present 25

26. Roundabout specialised at grade intersection introduces unidirectional circular movements. 26

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. 27

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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.  30

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. 31

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 . 32

33. Reference Google IRC 92- 1985 AND IRC92-2017 (GUIDELINES FOR THE DESIGN OF INTERCHANGES IN URBAN AREA) YouTube 33

34. Thank you 34