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://ordnancesurv
ey.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/859cc9a079eca4b5556af04b
3aa6215c.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. 21