Question

The vehicle count obtained in every 10 minute interval of a traffic volume survey done in peak one hour is given below. \[ \begin{array}{|c|c|} \hline \text{Time Interval (in minutes)} & \text{Vehicle Count} \\ \hline 0 - 10 & 10 \\ 10 - 20 & 11 \\ 20 - 30 & 12 \\ 30 - 40 & 15 \\ 40 - 50 & 13 \\ 50 - 60 & 11 \\ \hline \end{array} \] The peak hour factor (PHF) for 10 minute sub-interval is \(\underline{\hspace{1cm}}\) (round off to one decimal place).

Hint:

The Peak Hour Factor (PHF) is a ratio of the maximum vehicle count in any sub-interval to the average vehicle count across all intervals in the peak hour.

Answer 1

Correct Answer: 0.8

The Peak Hour Factor (PHF) is calculated using the formula: \[ PHF = \frac{\text{Maximum Vehicle Count in Any Sub-interval}}{\text{Average Vehicle Count per Sub-interval}} \] 1. First, calculate the average vehicle count for all the intervals: \[ \text{Average Vehicle Count} = \frac{10 + 11 + 12 + 15 + 13 + 11}{6} = \frac{72}{6} = 12 \, \text{vehicles}. \] 2. The maximum vehicle count in any 10-minute sub-interval is 15 (from the 30-40 minute interval).

3. Now, calculate the PHF: \[ PHF = \frac{15}{12} = 1.25. \] Thus, the Peak Hour Factor (PHF) is \( \boxed{1.25} \).