Traffic signal coordinated optimization of urban arterial road based on Petri net

To study the traffic signal coordinated optimization of urban arterial road, a timed Petri net model with a traffic signal display module and a signal phase transition module, and a traffic flow model based on continuous Petri net with variable speeds were established. A traffic signal control system composed of 3 subsystems for monitoring, discriminating and current phase selecting was designed, and concrete control steps were presented. Considering the relationship of parameters in continuous Petri net, next green phase was determined by taking vehicle queue length, traffic flow velocity at upstream section and open degree at downstream section as input variables, and phase priority indexes as output variables. The superior green time of current phase was determined by using fuzzy Petri net, and a simulation calculation was carried out. Simulation result indicates that by combining Petri net with fuzzy control, travel times respectively shorten by 7.1% and 7.6% for west-to-east and east-to-west traffic flow, and the improvement rates of queue length at intersection are 11.9% and 11.2% respectively. The average delays of four phases at intersection decrease from 9.7, 10.3, 11.8, 13.2 s to 8.2, 9.1, 11.4, 11.4 s respectively. So, traffic signal coordinated control on urban arterial road is better realized by using traffic signal coordinated optimization method.