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For a portion of national highway where a descending gradient of 1 in 25 meets with an ascending gradient of 1 in $20,$ a valley curve needs to be designed for a vehicle travelling at $90 \mathrm{kmphbased}$ on the following conditions.
(i) headlight sight distance equalto the stopping sight distance (SSD) of a level terrain consideringlength of valley curve $>\mathrm{SSD}$
(ii) comfort condition with allowablerate of change of centrifugal acceleration $=0.5 \mathrm{~m} / \mathrm{sec}^{3}$.
Assume total reaction time $=2.5$ seconds; coefficient of longitudinal friction of the pavement $=0.35$; height of head light of the vehicle $=0.75 \mathrm{~m} ;$ andbeam angle $=1^{\circ}$.

What is the length of valley curve (in $\mathrm{m}$ ) based on the head light sight distance condition?



Question ID - 155864 | SaraNextGen Top Answer

For a portion of national highway where a descending gradient of 1 in 25 meets with an ascending gradient of 1 in $20,$ a valley curve needs to be designed for a vehicle travelling at $90 \mathrm{kmphbased}$ on the following conditions.
(i) headlight sight distance equalto the stopping sight distance (SSD) of a level terrain consideringlength of valley curve $>\mathrm{SSD}$
(ii) comfort condition with allowablerate of change of centrifugal acceleration $=0.5 \mathrm{~m} / \mathrm{sec}^{3}$.
Assume total reaction time $=2.5$ seconds; coefficient of longitudinal friction of the pavement $=0.35$; height of head light of the vehicle $=0.75 \mathrm{~m} ;$ andbeam angle $=1^{\circ}$.

What is the length of valley curve (in $\mathrm{m}$ ) based on the head light sight distance condition?

1 Answer
127 votes
Answer Key / Explanation : (308 to 311) -

308 to 311

127 votes


127