Modeling of peak hour factor on highways and arterials

Abstract

The peak hour factor characterizes the fluctuations of traffic flow based on the busiest 15 minutes during the peak hour. This parameter is used in the process of evaluating the traffic flow conditions such as capacity and Level of Service. The paper examines the impact of traffic on the PHF, and results in calibrated models that estimate the PHF of different road categories based on a large data set obtained from a recent cordon and screen line traffic survey of Tel Aviv metropolitan area in Israel. The PHF was estimated for four road categories based on the independent variables: total number of vehicles per lane per direction, total number of trucks per direction, and total number of buses per direction. The PHF resulted in the following ranges, based on the superior calibrated models with or without the impact of the heavy vehicle variables: 0.88–0.99 for rural freeways and multilane highways, 0.81–0.97 for two-lane rural highways, 0.922–0.972 for urban and suburban freeways and multilane highways, and 0.91–0.98 for urban arterials. These volume based ranges partially include the uniform values proposed by the Highway Capacity Manual (2000, 2010). The rural model calibrations could be beneficial in estimating traffic flow rates for traffic engineering analysis when traffic counting is incomplete or not achievable. The urban models need further examination.