Traffic Simulation of Incident-Based Urban Expressway

Due to the lack of accurate traffic simulation model of congestion formation caused by road capacity sharp drop-down with incidents,an improved cell transmission model was presented to simulate the traffic congestion forming and diffusing process due to road capacity dramatic drop-down in the traffic incident. The improved model is able to avoid the uniform cell length limitation by introducing the cell density and cell length two parameters to depict cell internal state; meanwhile,the traditional simple linear traffic flow model was replaced with the three-phrase theory with hysteresis loop characteristics observed from real traffic phenomenon,to extend the applicability of the model. Simulation results indicate that the incorrect rate of the improved cell transmission model can effectively meet the modeling demands of reality traffic congestion evolution characteristics with incidents in urban expressway system,which provides conditions to uncover the congestion propagation principle.