A vertical summit curve is formed by n1 = + 2.5% and n2 = – 2.5%. The available stopping sight distance is 120 m. Calculate the length of summit curve to meet the intermediate sight distance.
- A280 m
- B300 mCorrect
- C320 m
- D340 m
Solution
Concept
Intermediate sight distance
Formula
L = N S²/9.6
Step-by-step solution
1. ISD = 2 SSD = 240 m; N = 0.05. 2. L = 0.05 × 240²/9.6 = 300 m.
Explanation
Both eye and object heights are 1.2 m for ISD.
Why the other options are wrong
Other values differ.
Shortcut
ISD = 2 SSD.
Correct answer: B) 300 m