The average delay used to determine the level of service at intersections is influenced by various factors. In this research project, we evaluated the methods to calculate the delay based on the HBS (2015). For some aspects, we identified a potential for improvement and suggest some approaches for adaptation. The empirical basis of the project were video measurements at 21 different intersections. The measurements were supplemented by simulations, which were preceded by an extensive calibration process. At signalized intersections, the comparison of measured and simulated delays with those calculated by HBS (2015) has shown that the delays are usually of a similar scale. The following possible improvements have been identified for separate components of the calculation methods: The influence of instationarity at signalized intersections should be replicated with a modified instationarity factor in order to also take into account asymmetric traffic flows in the peak hour. The influence of the longitudinal slope on the saturation flow and the influence of pedestrians and cyclists on the capacity of turning traffic flows should be further investigated, since discrepancies were found at the examined intersections. The delay calculation at unsignalized intersections should be modified slightly to reflect the influence of the capacity more precisely. Furthermore, a reference manual for HBS-compliant microscopic simulations of intersections could be useful to enhance the practical application of simulation in this field. (Author/publisher)
Abstract