Highway engg.

what is stopping sight distance & PIEV theory

1. 1 Prepared by , khushboo patel ( B.E civil engg .) Highway engineering

2. SIGHT DISTANCE Definition : The actual distance along the road surface , which a driver from a specified height above the carriageway has visibility of stationary or moving object is known as sight distance. 2

3. Restrictions to sight distance may be caused as shown in fig. Sight distance at horizontal curve http://www.tpub.com/inteng/11.htm16.gif 3

4. Sight distance at vertical curve http://www.msha.gov/training/surfhaul/images/slide6.jpg 4

5. Sight distance at intersection http://onlinemanuals.txdot.gov/txdotmanuals/rdw/images/3-2.png 5

6. 6

7. Stopping sight distance (SSD) Definition : The minimum sight distance available on a highway to stop a vehicle travelling at design speed , safely without collision with any other obstruction is xalled stopping distance. https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcQFKpIxAAAbJH3n64ECpY2EHIf-mjYUXedmQ0WUPheL5hqfngHS 7

8. http://www.ite.org/css/online/img/Figure10-5.jpg For the purpose of measuring stopping sight distance , IRC has suggest clear sight triangle as shown in fig. , 8

9. Factors affecting stopping sight distance 9

10. 1) speed of vehicle : https://encrypted/tbn1.gstatic.com/images?q=tbn:ANd9GcTJk56HWGT5GXbpWSsGFElb5384HgIeyKfqcB4cqKwu9xy69dSm 10

11. 2) total reaction time of the driver : http://www.hk/phy.org/contextual/mechanics/kin/eq_motion/6-01.gif 11

12. 3) friction resistance between the road & tyres : https://www.koroad.or.kr/images/en/img_know38.jpg 12

13. 4) gradient of road : 13

14. http://webarchive.nationalarchives.gov.uk/20061101091400/http://ordnancesurvey.co.uk/images/userImages/misc/education/gradient.gif 14

15. Analysis of SSD: 15

16. Lag distance Definition : The distance travelled by the vehicle during the total reaction time is known as lag distance . Reaction time of the driver is the time taken from the instant the object is visible to the driver to the instant the brakes are effectively applied . http://www.hk/phy.org/contextual/mechanics/kin/eq_motion/6-01.gif 16

17. What is PIVE Theory ? Acc. To PIVE theory the total reaction time of the driver is split into four parts . 17

18. 1) Perception time : It is the time required for the sensations received by the eyes or ears to be transmitted to the brain through the nervous system . 2) Intellection time : It is the time required for understanding the situation. 18

19. http://www.arrivealive.co.za/images/stoppingdistance.jpg https://m2.behance.net/rendition/pm/703187/disp/859cc9a079eca4b5556af04b3aa6215c.png 19

20. 3) Emotion time : it is time elapsed during emotional sensations & Disturbance such as fear , anger ,etc. with reference to the situation . 4) Volition time : volition time is the time taken for the final action. 20 Lag distance = v * t Where, v = speed of vehicle in m/s t = total reaction time (s) [ as per IRC t = 2.5 s ]

21. Have a nice day. 21