Sight Distance-Stopping Sight Distance, Overtaking Sight Distance.pptx

Sight Distance-Stopping Sight Distance, Overtaking Sight Distance, Sight Distance at Intersection

1. Presented By:- SUPREETH M.Tech (CTM) SIGHT DISTANCE 1

2. 2 SIGHT DISTANCE CONTENTS INTRODUCTION TYPES OF SIGHT DISTANCE STOPPING SIGHT DISTANCE OVERTAKING SIGHT DISTANCE SIGHT DISTANCE AT INTERSECTION

3. 3 SIGHT DISTANCE INTRODUCTION Sight Distance is the length of the road visible ahead to the driver at any instance. Fig.1:- Sight Distance at Horizontal Curve A B

4. 4 SIGHT DISTANCE Fig.2:- Sight Distance at Vertical Curve Fig.3:- Sight Distance at Intersection B A 2 1

5. 5 SIGHT DISTANCE TYPES OF SIGHT DISTANCE Stopping or Absolute Sight Distance. Safe Overtaking or Passing Sight Distance. Safe Sight Distance for entering into uncontrolled Intersection.

6. 6 SIGHT DISTANCE STOPPING SIGHT DISTANCE Fig.4:- Stopping Sight Distance It is a minimum sight distance available on a road at any spot should be of sufficient length to stop a vehicle travelling at design speed, safely without collision.

7. 7 SIGHT DISTANCE STOPPING SIGHT DISTANCE Fig.5:- Stopping Sight Distance Equation

8. 8 SIGHT DISTANCE SSD SPECIFICATION AS PER IRC 73 & 86 Table.1:- IRC Specification of Stopping Sight Distance

9. 9 SIGHT DISTANCE Stopping Sight Distance Depends on Factors Listed Below:- Total reaction time of the driver. Speed of vehicle. Efficiency of brakes. Frictional resistance between the road and the tyres. Gradient of the road.

10. 10 SIGHT DISTANCE OVERTAKING SIGHT DISTANCE The minimum distance open to the vision of the driver of a vehicle intending to overtake slow vehicle ahead with safety against the traffic of opposite direction is known as the overtaking sight distance or the safe passing sight distance. Fig.6:- Overtaking Sight Distance in Two-way Traffic

11. 11 SIGHT DISTANCE OVERTAKING SIGHT DISTANCE In One-Way Traffic, Overtaking Sight Distance is, OSD = d 1 + d 2 In Two-Way Traffic, Overtaking Sight Distance is, OSD = d 1 + d 2 + d 3

12. 12 SIGHT DISTANCE OVERTAKING SIGHT DISTANCE For Two Way Traffic OSD = d 1 + d 2 + d 3 OSD = V b t + V b T + 2S + VT ,m (V in m/sec) OSD = 0.278V b t + 0.278V b T + 2S + 0.278VT ,m (V in kmph) For One Way Traffic OSD = d1 + d2 OSD = Vbt + VbT + 2S ,m (V in m/sec) OSD = 0.278Vbt + 0.278VbT + 2S ,m (V in kmph)

13. 13 SIGHT DISTANCE OVERTAKING SIGHT DISTANCE AS PER IRC 73 Design Speed ( kmph ) Safe Overtaking Sight Distance (m) for two way traffic 40 165 50 235 60 300 65 340 80 470 100 640 Table.2:- IRC Specification of Overtaking Sight Distance

14. 14 SIGHT DISTANCE Overtaking Sight Distance Depends on Factors Listed Below:- Speed of Overtaking vehicle, Overtaken vehicle and Opposing vehicle. Distance between overtaking and overtaken vehicle. Skills and Reaction time of the driver. Rate of acceleration of overtaking vehicle. Gradient of the road. Time required for overtaking operation.

15. 15 SIGHT DISTANCE OVERTAKING ZONE Fig.7:- Overtaking Zone

16. 16 SIGHT DISTANCE SIGHT DISTANCE AT INTERSECTION Fig.8:- Sight Distance at Intersection At all approaches of intersecting roads, there is a clear view across the corners from a sufficient distance so as to avoid collision of vehicles .

17. 17 SIGHT DISTANCE The sight line is obstructed by structures or other objects at corners of intersection. The area of unobstructed sight formed by the lines of vision is called the Sight Triangle.

18. 18 SIGHT DISTANCE The design of sight distance at intersections may be based on three possible conditions:- Enabling the approaching vehicle to change speed. Enabling approaching vehicle to stop. Enabling stopped vehicle to cross a main road.

19. 19 SIGHT DISTANCE Apart from these three situations mentioned above, the following sight distance are considered by the IRC in highway design :- Intermediate Sight Distance. Headlight Sight Distance.

20. 20 SIGHT DISTANCE INTERMEDIATE SIGHT DISTANCE It is defined as twice the stopping sight distance. When overtaking sight distance can not be provided, intermediate sight distance is provided to give limited overtaking opportunities to fast vehicles. ISD = 2 (SSD)

21. 21 SIGHT DISTANCE INTERMEDIATE SIGHT DISTANCE AS PER IRC 73 Speed ( kmph ) Intermediate Sight Distance (m) 20 40 25 50 30 60 35 80 40 90 50 120 60 160 65 180 80 240 100 360 Table.3:- IRC Specification of Intermediate Sight Distance

22. 22 SIGHT DISTANCE HEADLIGHT SIGHT DISTANCE This is the distance visible to a driver during night driving under the illumination of the vehicle head lights. This sight distance is critical at up-gradients and at the ascending stretch of the valley curves. Fig.9:- Headlight Sight Distance

23. 23 SIGHT DISTANCE THANK YOU