What does the Peak Hour Factor (PHF) measure?

The Peak Hour Factor (PHF) is a critical concept in traffic engineering and planning. It measures the fluctuation in traffic flow during the peak hour of traffic, capturing how traffic volumes can vary within that hour. Specifically, PHF provides a way to account for the uneven distribution of traffic that commonly occurs within the peak hour, which is often not uniform.

By using the PHF, traffic engineers can assess the efficiency of roadways and intersections, taking into consideration the variability in traffic flow. This information is essential for accurate capacity analysis and for designing facilities that adequately accommodate the stress of peak traffic conditions.

Other options do not align with the definition of PHF. For instance, measuring the rate of traffic accidents pertains more to safety analysis than to traffic flow characteristics. The average speed of vehicles during peak hours is a distinct metric that does not relate to the variability in traffic volume, while the number of vehicles passing a point in one hour relates to capacity measures rather than fluctuations in traffic flow. Thus, the correct understanding of PHF lies in recognizing it as a measure of the fluctuation in traffic flow during peak periods.