Occurrence and Impact of Passing Maneuvers in Nonmotorized Mixed Traffic of Bicycles and Mopeds

Passing is an important element of a microscopic traffic simulation model and an index of LOS evaluation. As the passing events between mopeds and bicycles occur frequently in the mixed non-motorized traffic, it is necessary to study the characteristics of the occurrence and impact of passing events. In this paper, how often the passing events between mopeds and bicycles occur, who performs the passing maneuvers more frequently, under what circumstances they occur, what indicates the initiation of passing maneuvers, and how much passing mopeds impact the passed bicycles were analyzed separately. Two observation sites in Shanghai were chosen for this research. The locations of bicycles and mopeds every 0.5 s under free flow condition and during passing maneuvers were obtained from the video recordings through MATLAB. Thus, the parameters such as speeds, the lateral distances from right edge of lane and the space headway were analyzed. The mopeds were found to pass the bicycles frequently because of the significant speed differences between them. The initiation of passing maneuvers was defined, and the speed difference before passing and the space headway before passing were found to be positively correlated based on the definition. The strong impact of passing mopeds on passed bicycles even under low traffic flow densities was also proved. These findings provide valuable references for roadway design and policy making. They also support the future studies on simulation and LOS of mixed non-motorized traffic.