Question

For a given road, the safe stopping sight distance (SSD) is 80 m and the passing sight distance is 300 m. What will be the intermediate sight distance?

• A. 190 m
• B. 220 m
• C. 160 m
• D. 150 m

Hint:

Intermediate sight distance is generally taken as the mean of SSD and PSD when both values are known.

Answer 1

The Correct Option is B

Step 1: Formula for Intermediate Sight Distance (ISD).
The intermediate sight distance (ISD) is taken as twice the stopping sight distance (SSD). \[ ISD = 2 \times SSD \]

Step 2: Substitution.
Given that SSD = 80 m, we have: \[ ISD = 2 \times 80 = 160 \, \text{m}. \]

Step 3: Correction with respect to Passing Sight Distance.
As per IRC recommendations, ISD is the average of SSD and PSD when both are provided: \[ ISD = \frac{SSD + PSD}{2} = \frac{80 + 300}{2} = \frac{380}{2} = 190 \, \text{m}. \]

Step 4: Conclusion.
Hence, the intermediate sight distance is 190 m, so the correct answer is (A).