Studies On Intelligent Freeway Control Methods

Freeway traffic control is considered as an important component of intelligent transportation system. For the drawbacks of traditional traffic control techniques, people have begun to apply advanced theories and techniques to freeway traffic control in recent years. Several intelligent methods for freeway traffic control have been presented and discussed in detail. Combined intelligent control theories with other advanced techniques, several important problems of freeway traffic control have been studied.The following researches are involved in this paper:1. A dynamic recurrent neural network to freeway macroscopic traffic flow modeling is presented. A discrete mathematical model of freeway traffic flow is analyzed. The Elman recurrent neural network model is built and an improved algorithm is used to obtain the weights of the neural network. The recurrent neural network is applied to a freeway with five segments. Simulation examples show that the Elman recurrent neural network can approach the mathematical model of traffic flow with high accuracy. Compared with the models of back propagation and radial basis function neural networks, the Elman recurrent neural network has the fewest training epochs, the smallest error and the best generalization ability. The Elman recurrent neural network can describe the real behavior of traffic flow accurately and speedily.2. A fuzzy logic approach is proposed to regulate the number of vehicles entering a freeway entrance point during rush traffic times. The basic structure of a fuzzy logic controller is analyzed and the fuzzy control algorithm is formulated. The membership functions are developed and the fuzzy logic on-ramp controller is designed based on such traffic information as the flow, speed, occupancy, and ramp queue length. These variables are each measured by several sensors built into the upstream, downstream, and on-ramp portion of the freeway. Simulation results show that such an approach is practical and effective. It can avoid traffic jams and congestion on the mainline, improve the passing capability, and make the vehicles travel more efficiently and safely.3. A nonlinear feedback method is proposed for on-ramp metering by using fuzzy logic. The freeway traffic flow dynamic model is built. Based on the model and in...