The Study On Complex And Dynamic Characteristics Of Traffic Flow And Traffic Jams

The emergence of cars brings forth great conveniences for travel,improves the efficiency of social traffic,promotes development and progress of society and has changed the social structure.But on the other hand, with the rapid economic development and the increasing car ownership, the traffic problem, such as deteriorating congestion,traffic accidents and environmental pollution, has become an obstacle to urban development all over the world.In recent years, frequent abnormal events around the world, such as freezing rain and snow events in South China,Wenchuan and Haiti earthquakes etc., are putting forward higher and new requirements for road transport systems. When abnormal events occurs, the original complex transport system could become more uncertain and nonlinear. So the applicability of the existing traffic theories and methods in normal environments would become significantly inadequate in the state of abnormal events. Researchers on various disciplines have recognized the complexity of traffic flow which has attracted many traffic scientists, mathematicians, physicists and economists into this area. It is very important for the guidance of effective solution of traffic problem fundamentally to make some breakthroughs in traffic science. Traffic flow theory is the basis for the traffic science development, but now the serious lag of traffic flow theory development has restricted the development of traffic science, and even has become a serious bottleneck to solve traffic problems.Based on the National High Technology Research and Development Program (863 Program), "research on key technologies of a novel generation of intelligent traffic control system " and the National High Technology Research and Development Program (863 Program), " research on the road traffic abnormal information collection under the abnormal state " , this dissertation is completed.Transportation system is a typical, open, complex and dynamic giant system involving human, with a high degree of nonlinearity and uncertainty. Congestion adds to the uncertainty of its nonlinear and complex characteristics.How to find the certainty from uncertainty,the commonness from individuality ,becomes the research's key. The dissertation all the time has the aims to seeks to improve the efficiency of transport trip,to alleviate and solve traffic congestion, and makes it a research start point to study the relationship of the driver reaction time and driving distance,the main line to study the dynamic balance between driving speed and safety distance.On the basis of a large number of domestic and foreign literatures, this thesis firstly studies the complex factors affecting the micro- and macro- traffic flow dynamic characteristics; then analyses deeply the micro- traffic flow dynamic characteristics and macro- traffic flow dynamic characteristics from the qualitative and quantitative point of views,micro and macro levels separately, finally (combined with measured data) applying research results of complex traffic flow dynamic characteristics, describes the complexity phenomenon and cause of traffic flow;discusses the formation,development and evolution of recurring and non-recurring two types of traffic congestion; reveals the formation mechanism of the traffic jam, proposes congestion recognition algorithm, traffic state assessment and traffic information collection methods.This thesis is composed of the six interrelated components. Main research contents are as follows:Chapter One Firstly ,this part introduces the thesis background, purpose and meaning, explaines the complexity of traffic flow, traffic flow at home and abroad were reviewed micro and macro theories of the main research results, discusses the theoretical model of traffic flow generally thought, given the text of the main research content framework and research technical line.Chapter Two This section carries out influencing factors study of the dynamic complexity of traffic flow from the two aspects of the normal and abnormal traffic enviroments. Under normal traffic enviroment, this thesis studies the driver's dynamic vision, reaction time, psychological and physiological characteristics; the car's dynamic performance and braking performance impacts on traffic flow; discusses the road alignment and road surface conditions' impacts on vehicular traffic safety; when there are the abnormal events, in addition to the influences under normal states, the paper analyzes abnormal events' impacts on the connectivity of road network, traffic capacity, traffic demand, travel time and traffic safety, etc. .Chapter Three Microscopic traffic flow characteristics are the basis of macroscopic traffic flow research. Microscopic traffic flow headway will affect the driving behavior, traffic safety, traffic capacity and service level etc.. Hence it is an important traffic flow parameter,which has a direct impact on changes in driving behavior of vehicles. Its critical minimum headway controls vehicle traffic safety and decides road capacity. On the other hand, headway interval distribution is also of great significance for the study of intersections and other traffic conflicts through gaps. Through in-depth study of traffic flow parameters of microscopic traffic flow dynamic characteristics and traffic flow space-time diagram,this section establishes a new speed density relationship; through in-depth analysis of existing car-following models, this section proposes an improved car-following model,and conducts its stability analysis and tests its validity with the experimental data.Chapter Four Macroscopic traffic flow characteristics are traffic flow groups behaviors of microscopic individual performance. Traffic density, average speed and traffic flow volume are the basic and most important three parameters in macroscopic traffic flow characteristics, These three parameters are to study the temporal and spatial changes in traffic flow dynamic characteristics from a macroscopic aspect. On the basis of microscopic traffic flow theory, this section studies traffic flow parameters expression of the macroscopic characteristics and the dynamic relationships between traffic flow three parameters, deduces fluid dynamics theories and traffic-wave models, proposes an effective traffic capacity and residual capacity concepts at the first time, and makes a comparative analysis between traffic flow and real fluids. Finally, this section describes the traffic flow chaos and self-organization phenomena, and gives the study ideas of traffic flow complexity.Chapter Five Starting from the understanding of traffic congestion, using the aforementioned research results, this section analyzes the phenomena of traffic congestion, discusses the two types of familiar traffic congestions, studies the spatial and temporal distribution characteristics of traffic congestion. From three different levels, this section gives an in-depth analysis of the causes of traffic congestion, discusses the two types of special traffic congestion phenomena. Based on traffic flow fundamental diagram, this dissertation corrects the theoretical arrival - departure capacity curve. And furthermore, this paper establishes a congestion detection algorithm based on the kinematic equation, and discusses the transmission problem of the congestion using the traffic wave theory. Finally, Based on the congestion evaluation approaches of advanced countries, this section gives some principles and attention points for the establishment of traffic congestion evaluation indices and introduces traffic information collection technologies for the analysis and evaluation of traffic congestion.Chapter Six The thesis research results and innovative productions are summarized. Furtherly,the paper points out future directions for further research.