Study on at-grade intersection spacing of highways using microscopic traffic simulation

Safety performance of highways has always been the focus of traffic engineering studies. Although many factors impact safety of highway transportation, at-grade intersection spacing is by far one of the most important factors. In reality, many situations can lead to closely neighbored intersections which become major causes of traffic accidents. To improve safety, intersection spacing should guarantee that vehicles from upstream intersection can be stabilized before coming to the next intersection. Therefore, minimum intersection spacing should be satisfied. By exploring characteristics of traffic flows released from upstream intersection, the paper has put forward a study approach, which analyzes safety state of vehicles by examining speed index CSV (coefficient of speed variance). Using microscopic traffic simulation software TSIS (traffic software integrated system), simulation models for the study have been built up and calibrated. Finally, based upon analysis of data from simulation, standards for minimum intersection spacing of highways are given.