Urban Intersection Signal Timmg Design Based On Vissim Simulation

In recent years, urban traffic congestion problem has become more and more serious with the development of society and economy as well as the acceleration of urbanization. Now it becomes a worldwide problem. The urban intersection is not only an important part of urban traffic but also a place where congestion is most serious. Many approaches can be used to improve the efficiency of the urban intersection, but a reasonable signal control strategy is generally the most effective way. Actually urban traffic is a complex system with strong nonlinearities. On the basis of the existing road resource, applying advanced control methods to the urban traffic system has become a tough problem which needs to be solved in a short time.In this paper, both a time-delay based fixed timing algorithm and an iterative learning control based intersection signal control approach are proposed respectively to improve the efficiency of urban intersection. The former considers a time-delay index as the main factor in signal timing, and thus the time-delay can be reduced by the new designed algorithm. The latter can consider the periodicity and repeatability characters of urban traffic and a good performance can be achieved by learning from previous cycles. The main contents and contributions of this work are summarized as follows:1) The characters and difficulties of urban signal control are explored firstly, and then we provide a simple introduce about the development and practical applications in of the urban signal control. Some further research on the control parameters and evaluation index during signal control process has also been done in this work. Different from the signal timing principle of classical control systems, the work of this paper is mainly focused on model building and signal control design.2) In order to describe the change of traffic flow accurately, the macroscopic traffic model about urban signal control is established. Then in this work, we further introduce the model of speed-flow, which plays an important part on the design of signal control and simulation research. The formulation of running qualities of vehicles on the intersection during signal control process is proposed, and then a fixed timing method based on time delaying is proposed. Three phase signal timing design is presented by combining VISSIM platform, which is a microscopic traffic simulation tool. Before staring simulation, it is necessary to establish the urban road network. All the parameters are input to VISSIM, and then one can begin the real-time simulation. The results of the simulation show that the method proposed in this paper is effective.3) Considering the repeatability and periodicity of urban traffic control system, a new iterative learning control approach based signal control of urban intersection is proposed for the signal timing of urban intersection. Using the idea of balance control, the performance index is that queue length difference of different phase is up to minimum, and also the signal control strategy can be adjusted with the change of traffic flow. The evaluation of signal timing strategy proposed in the work is achieved with the help of VISSIM simulation tool. Compared with fixed timing method, iterative control of urban signal timing is better in the evaluation index including queue length difference, total vehicle and average delaying. Therefore, the simulation results show that the signal control method based on ILC is more suitable to solve the urban congestion.