What is the formula used for the peak hour factor calculation?

The peak hour factor (PHF) is a critical measure used in traffic engineering to evaluate the distribution of traffic flow over a specific time period. It essentially compares the peak hour volume to the total volume during a longer observation period, allowing engineers to assess how concentrated traffic is during peak times.

The correct formula for calculating the peak hour factor uses the total volume observed during the peak hour and relates this to the volume during shorter intervals. The formula typically utilized is:

Peak Hour Factor (PHF) = Volume / (Total Volume over a longer period divided by the number of intervals in that period).

In the context of this question, the expression suggests that you are expressing the peak hour volume in relation to a measured volume over a specific time. The correct answer indicates that you take the volume (which would refer to the peak traffic volume during a specified time) and relate it to one-fourth of the total volume. This is because the total volume represents the sum of flows over a longer observation period, often quartered to understand the flow relative to peak traffic trends better.

The formula thus emphasizes that the volume during a specific peak hour is divided by four times the volume measured over shorter intervals, allowing for the assessment of how much traffic is concentrated during