Delays caused by motorized vehicles unable to clear intersections in China: Graphical analysis

In many Chinese cities, motorized vehicles (M-vehicles) move slowly at intersections due to the interference of a large number of non-motorized vehicles (NM-vehicles). The slow movement makes a part of M-vehicles fail to leave intersections timely after the traffic signal turns red, and thereby conflicts between vehicles from two directions occur. The phenomenon was analyzed graphically by using the cumulative vehicle curve. Delays in three cases were modeled and compared: NM-vehicle priorities and M-vehicle priorities with all-red intervals unable to release all vehicles, and longer all-red intervals ensuring release all vehicles. Marginal delays caused by two illegal behaviors that occasionally happened in mixed traffic intersections were also investigated. It is concluded that increasing the speed of M-vehicles leaving intersections and postponing the entering of NM-vehicles are the keys in mathematics, although they are uneasy in disordered mixed traffic intersections due to a dilemma between efficiency and orders in reality. The results could provide implications for the traffic management in the cities maintaining a large number of M- and NM-vehicles.