Abstract
This paper studies peak flow factor (PFF) characteristics through analysis of the peak interval flow rate, the peak hourly volume, and the stability of their dynamic relationship. Despite wide recognition of the importance of the peak hour factor (PHF) in traffic studies, including capacity and level of service evaluation as well as measures of effectiveness analysis of highways and intersections, limited research has focused on PHF characteristics that are affected by variations of traffic conditions during the peak hour. The statistical properties of the PFF are analyzed and its changing patterns are compared at peak time intervals varying from 3 to 20 min. Field data from freeways, signalized intersections, and unsignalized intersections were used in the analysis. Results showed that the PFF became larger with an increase in the peak time interval and remained relatively stable for time intervals of 5 min or more for freeways and 10 min or more for intersections. Reliability tests indicated that the results of the PFF analysis based on field data were highly dependable.
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