Freeway traffic flow control by lumped parameter system approach

Freeway traffic flows can be controlled by lumped parameter system approach owing to the space discretized system models. Such a control model incorporating a coordinated ramp metering mechanism is proposed in this study. The nonlinear state equations representing the traffic system dynamics are derived from the conservation law in difference equations form. The control model is obtained by a feedback linearization approach, so that the target density of the controller is chosen as the critical density of the traffic system. Simulation based test studies have been done in a VISSIM simulation environment in order to compare the data obtained by the shock wave modified feedback linearization method to the nonmodified type, with respect to the uncontrolled system performance. Test results show that the main-link flow performance is increased sufficiently by the proposed control model.