Civil Engineering - UPSC Civil Service Exam Questions - Discussion

Discussion Forum : UPSC Civil Service Exam Questions - Section 1 (Q.No. 9)
9.
For total reaction time of 2.5 seconds, coefficient of friction 0.35, design speed 80 km/h, what is the stopping sight distance on a highway ?
127 m
132 m
76 m
56 m
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
13 comments Page 2 of 2.

Jaspreet singh said:   1 decade ago
Ssd = 0.278vt+0.039v^2/a.

v = Design speed, km/h.
t = Brake reaction tim, 2.5 sec.
a = Deceleration rate, 3.4m/s^2.

ASHISH said:   1 decade ago
SSD = lag dist + breaking dist.

= (0.278*v*t) + (v*v/254*f).

= (0.278*80*2.5) + (80*80/254*0.35).

= 127.59.

v in km/hr.
(1)

Danesh said:   1 decade ago
SSD = LAG DISTANCE + BRAKING DISTANCE.

= v*t + v^2/(2gf).

= 22.22*2.5 + 22.22^2/(2*9.81*0.35).

= 127.45m.

Where "v" in m/s.
(1)


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