Research On Optimal Design And Microscopic Simulation Of Isolated Signalized Intersection

This paper mainly describes the optimal design of isolated signalized intersection. It includes geometric design, traffic organization design and signal timing of signalized intersection. The techniques of expert system and computer-based simulation are employed. Several schemes that are generated from expert system of signalized intersection design are inputted into microscopic simulation system, and then optimal scheme is put forth.Firstly, the research history of signalized intersection is reviewed. Several popular and classical traffic control systems, such as TRANSYT, SCATS and SCOOT are analyzed. Moreover, some achievements in research of signalized intersection are earned in China. However, the start of studying signalized intersection is too late. Most of works we have done are only drawing lessons from foreign advanced experiences. Based on the situation of optimal design of signalized intersection, a System of Optimal Design of Signalized Intersection was put forth. The system consists of two sub-systems: the Expert System of Signalized Intersection and the Simulation System of Signalized Intersection.Secondly, the Expert System of Signalized Intersection is introduced. The system includes sub-system of geometric design, sub-system of signal timing and sub-system of traffic organization. Several techniques are discussed, when establishing this system. The Expert System of Signalized Intersection initiates a new research field of urban road traffic management.Thirdly, the sub-system of signal timing is presented. It is pointed out clearly that the design of signal phase plays an important role in signal timing. There is a strong relationship between the phase design and signal timing. The paper pays much attention to the expert system of multiphase design. The system frame of knowledge-based signal timing theory is put forward. At the same time, a comprehensive knowledge database has been created. According to the traffic flow characteristics of signalized intersection, phase order generation model and optimal phase design model are established. Then on thebasis of critical phase, signal timing model is established to guarantee the rationality of multiphase signal timing scheme.Fourthly, a microscopic computer simulation model, SIMSIO (Simulation Model of Signalized Intersection Operations) is established on the basis of some advanced sub-models for traffic simulation in order to simulate the characteristics of traffic flow in our country.. The various ways of modeling traffic behavior are discussed and the selection and calibration of these mechanisms with field observations are described. Validation studies show that SIMSIO provides a good representation of actual conditions. SIMSIO can provide a flexible and efficient experiment analysis tool that can be used to evaluate signal timing, geometry design and traffic management of signalized intersections, as well to test as new techniques and concepts.Finally, application of SIMSIQ in Intelligent Transportation System Is viewed as a prospective trend. It is pointed out that the future development of expert system and simulation system are intelligent and integrated.