Cellular Automata Method And Its Application In Traffic Flow

With the development of urban social economy, the contradiction between the growth of traffic volume and the road condition is becoming prominent, which has greatly restricted the development of social economy. In recent years, many scholars in different fields have taken traffic problems seriously. The research of Cellular Automata traffic flow model has been concerned for its capability in dealing with non-linear problems. It can reflect various complicated factors existing in traffic process with simple rules, and also can be realized with computer, thus illustrating the effect of the factors on the urban traffic behavior conveniently.Some major traffic stream models and the basic theory of Cellular Automata were introduced in the paper. The characteristic of Cellular Automata as a non-linear model was emphasized. The probability of Cellular Automata modeling in traffic flow was reasonable for several successful applications in some areas.The overview of green-wave model, braking effect and steering probability effect were generalized on the basis of the existing research on Cellular Automata traffic flow model. The affection of many factors to be considered in the practical traffic system was summarized. The conclusion was analyzed and drawn that all the stochastic factors in the one-dimensional Cellular Automata model had the same effect on traffic flow qualitatively. The consequent agreement in the behavior of the asymptotic steady state of the "corrective NS model" and FI model was discussed and the importance of random delay style was considered.The open-boundary Cellular Automata traffic flow model in accordance with the practice was raised and simulated numerically on the basis of BML model. The jamming phase of zero average velocity did not occur when the density of vehicles was not high. The boundaries had sufficient capacity to offer and hold the vehicles that moved in or out. The density of vehicles would tend to a certain stable value with the acceleration of time step, which could reflect that the urban traffic had appropriate capacity. Although the growth of vehicles' density would decrease the velocity and increase the rate of jamming, it could greatly increase the vehicles that passed the urban areas, which might enhance the availability of the urban express highway consequently.The simulation model for traffic flow was discussed initially by analyzing the characteristic of the traffic flow in urban express highway.