Step 1: Intermediate Sight Distance (ISD) Formula.
Intermediate sight distance (ISD) is defined as twice the stopping sight distance (SSD). \[ISD = 2 \times SSD\]
Step 2: Calculation.
With SSD = 80 m, the calculation is: \[ISD = 2 \times 80 = 160 \, \text{m}.\]
Step 3: Adjustment for Passing Sight Distance (PSD).
According to IRC guidelines, ISD is the mean of SSD and PSD when both are specified: \[ISD = \frac{SSD + PSD}{2} = \frac{80 + 300}{2} = \frac{380}{2} = 190 \, \text{m}.\]
Step 4: Final Result.
The intermediate sight distance is therefore 190 m, corresponding to option (A).
Match LIST-I with LIST-II (adopting standard notations):\[\begin{array}{|c|c|} \hline \textbf{LIST-I (Parameter)} & \textbf{LIST-II (Formula)} \\ \hline \\ \text{A. Cubic parabola equation} & \text{IV. $\dfrac{X^3}{6RL}$} \\ \\ \hline \\ \text{B. Shift in transition curve} & \text{II. $\dfrac{L^2}{24R}$} \\ \\ \hline \\ \text{C. Length of valley curve} & \text{III. $\dfrac{N S^2}{(1.50 + 0.035S)}$} \\ \\ \hline \\ \text{D. Length of summit curve} & \text{I. $\dfrac{N S^2}{4.4}$} \\ \\ \hline \end{array}\] Choose the most appropriate match from the options given below: