Retracted: Coordinated Multi-ramp Control Based on Stratification Structure and Particle Swarm Algorithm

To further enrich highway ramp metering methods and enhance the control performance, a coordinated multi-ramp control method based on stratification structure and improved particle swarm algorithm (PSA) is proposed. Firstly, a cell transmission model (CTM) to describe the evolution process of highway traffic flow is formulated. Then, the system structure is designed. Moreover, the tasks of a coordinated control layer and direct control layers are determined. In the direct control layer, proportional-integral-differential (PID) controller is employed to implement control. Also, PSA is used to optimize the PID parameters. The optimization ability is improved by changing the inertia weight values and utilizing simulated annealing algorithms. Simulation example indicates that the control system can effectively eliminate congestion and maintain the stability of highway traffic flow when there exists highway congestion.