Capacity Analysis of Signalized Intersections under Mixed Traffic Conditions

This paper presents a new approach for calculating straight lane capacity under mixed traffic conditions, especially in China. The First Discharge Headway (FDH) is applied as a novel to improve Stop Line Method model, and the influencing factors of FDH are analyzed. To calibrate the FDH probability distribution, investigation data of four intersections in Beijing are employed. The Equivalent First Discharge Headway (EFDH) is proposed to replace the current empirical value in traffic capacity calculation. Using the improved model, the paper analyzes conflicting pedestrian and non-motor volumes' impact on capacity under mixed traffic conditions. The results show that FDH is only related to vehicle type and external disturbance factors (α<0.05), and there is no mutual influence between each other. The Weibull distribution could well be applied to describe the probability distribution of the FDH. Though the EFDH correction, the calculation error of capacity is reduced to less than 5%. The traffic capacity presents exponential decline with the increase of conflict frequency between pedestrians, non-motors and motorized vehicles, the conflict influence is diminishing marginal utility.