Study On The Complex Dynamic Properties Of Traffic Flow Based On Cellular Automata Model

With the continuous development of social economy, traffic demand rapidly increases. Therefore, transportation problem gradually becomes an emergent world problem, which influences human life greatly and limits economy development. How to make full use of the finite traffic resource, how to find the potential of existing infrastructure, how to guide the traffic designing, planning and management with scientific theory and how to alleviate the rapidly growing traffic supply and demand, all these become important problems to be solved. The study of traffic flow theory emerges as the times require. Recently, as a new cross subject, traffic flow theory have been paid attention by scientists on these aspects of mechanics, physics, nonlinear science, information science, traffic engineering, statistics, computer science and so on. The purpose of traffic flow theory is to describe traffic property by applying the advanced science knowledge. By founding appropriate model, carrying out computer simulation and mathematic analysis, we hope to discover the essential characteristics of traffic flow, provide reliable proof for traffic planning and managenment.After having sufficiently investigated the development of traffic flow theory, we put forward new traffic flow models according to the practical road situation. We have found a kind of nonlinear phenomena by simulation and theory analysis and discoved the physical characteristics of traffic models. The contents of the paper are as follows:We put forward an impoved two-route traffic flow model, in which we modified the two unreasonable aspects in previous works:(1) at every time step, a new vehicle is generated at the entrance of two routes; (2) if a new vehicle is not able to enter the desired route, it will be deleted. In our modified model, at every time step, a vehicle reaches the entrance with probabilityλand if the vehicle can not enter the selected route, it will stop and wait at the entrance. Theλis a random number between 0 and 1.In the first modified model, assume there is a limited speed bottleneck (for example, pedestrians go throught the road and a part of road is closed for working) on a route. We discussed the model in detail under mean velocity information feedback strategy and found that there exist four different system states in our model, i.e., zero state, periodic oscillation state, alternation state and equal velocity state. Furthermore, we also obtained the relationship between dynamic vehicles and critical vehicle arriving probability in zero state. On top of the previous work mentioned above, we have the model further developed. In the second modified two-route traffic model, the two routes are unequal and a limited speed bottleneck is sited on the shorter route, which is denoted as unsymmetrical two-toute system. Correspondin gly, the two-route system with the same routes is denoted as symmetrical two-route system. Because the previous information feedback strategies are invalid, we adopted improved mean velocity information feedback and improved congestion coefficient information feedback to study our modified model. The simulation results showed that the average cost of drivers is dependence on the vehicle arriving probabilityλ. It is able to save time under the improved mean velocity information feedback strategy when theλis small. However, it can save time under the improved congestion coefficient information feedback strategy when theλis large.In succession, we investiged the symmetrical and unsymmetrical two-route model when some static dynamic vehicle diobey the provided information. Simulation results showed that the high amplitude of average flux appearing on two routes is suppressed and the system capacity is enhanced. This indicates that, in some case (for example, drivers choose route in two-route system), it is not the best ways for divers obeying rules.Because the practical traffic system consists of lots of vehicles, at the same time vehicles is controlled by drivers with mind, the vehicles in traffic system can happen to compete each other. The competion is able to be described by evolutionary game. In this paper, it is the first time to introduce the evolutionary game into the one-dimensional road traffic system. Firstly, we investigated one road with periodic boundary condition. The simulation results indicated that the system is possessed of nontrivial critical behavior. There exists a critical density in our model. For large density, the fraction of cooperator maintains a nonzero constant. Contrarily, for small density, the fraction of cooperator decays exponentially. The introducing of defector decreases the mobility of vehicles. This model is able to describe pedestrian or biological traffic.As the extension for one road traffic, we have the model further developed and introduce the evolutionary game into two road traffic. Simulation results showed that when the share of cooperator increases, the region of low density enlarges, which indicates it can increase the mobility of vehicles when the share of cooperator increases.