Empirical Study of Phantom Traffic Jams on Urban Expressway

Traffic congestion is quite common in the city, and as one main reason for such issue, the driving behavior of illegal lane-changing should be analyzed. In this study, by focusing on the scenario of “phantom traffic jams” on urban expressway, we study the effect that the illegal lane-changing behavior made in a long run on the road, and try to deduce the patterns of congestion propagation in real time. We find that the illegal lane-changing behavior leaded to the serious traffic jams in the 4.5-kilometer-long road segment, and the phenomenon lasted for about 40 minutes. With analysis of the process of congestion propagation, we find that the propagation speed of congestion wave and the speed drop at each observation point declined continuously with fluctuation. The study outcome can be widely referenced in the fields of traffic management, and it is also ideal to support the adjustment of parameter in transportation simulation system.