What is Peak Hour Factor (PHF)?

The Peak Hour Factor (PHF) measures how steady traffic flows during peak hour. PHF compares the total traffic volume during the peak hour with the traffic volume during the busiest 15-minutes of the peak hour.

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                 Total Hourly Traffic Volume

PHF = ------------------------------------

            Peak 15-minute Traffic Volume x 4

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PHF = V / (V_max,15 x 4)

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The maximum and minimum PHF values are 1.00 and 0.25, respectively. A PHF of 1.00 indicates no variation in traffic flow within the analysis hour and a PHF of 0.25 indicates that the entire hourly volume occurred during the peak 15-minute interval.

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