Identification of spillovers in urban street networks based on upstream fixed traffic data

This paper presents a method to identify spillovers based on upstream fixed detector data, using occupancy per cycle as the determination index. The key idea of this new method is that when the queues extend to the detector position, there will be unusable green time to a certain degree, and the occupancy will be greater than a particular threshold. Firstly, this paper introduces traffic wave models modified by a kinematic equation, and provides a calculation method for the occupancy per cycle under different traffic conditions, based on the relationship between the three basic traffic flow parameters, speed, traffic flow, and density. Secondly, the threshold of occupancy, which characterizes the appearance of spillovers, is determined by the premise that the stopping and starting waves have the same speed, and then the accuracy of the new method are verified by VISSIM simulation, using the ratio of misjudgment as the evaluation index. Finally, the precision stability of the method is analyzed, and the results show that the precision of this method is affected by the the detector location and bus ratio insignificantly.