Analysis and simulation of traffic state on expressway during incident

In order to research the influence of incident on the traffic operation of expressway, the process of local traffic state during incident was disassembled, the capacity in each phase was analyzed, the affecting factors of the capacity were induced to incident feature, blocked width, incident position, travelling order and upstream traffic volume, and traffic microsimulation was carried out when accident results to the closure of some lanes.Simulation result shows that traffic delay increases quickly during the closure till the lanes are opened, then starts to decrease, there are some fluctuations in the whole process; when traffic volume approaches capacity, the balance of traffic system is weak, incident will arouse traffic congestion in large area and long time, some necessary measures, such as traffic routing and ramp control, should be adopted to divert traffic volume partially and reduce incident influence.