Study On Compressibility And Viscosity Of Traffic Flow

Lately, the number of cars has increased rapidly in our country, so conventional traffic establishments have not meet traffic demand. In addition, the development of city traffic is block because of the especial traffic status that vehicles and bicycles are mixed on road in our country. In order to improve traffic congestion aroused by the reasons above to advance traffic efficiency, traffic flow theories according to our country's fact should be researched. Moreover, there is desiderated and significant problem that traffic flow characteristics must be well known and according models established to apply them to engineer. Therefore, this thesis mainly studies on traffic flow compressibility and viscosity which enriches traffic theory.There was a long history for the development of studying on traffic flow characteristic and theory and lots of excellent fruits. On the base of these harvests, this article exploringly studies on traffic flow compressibility and viscosity applying the method of hydrodynamics. At first, traffic flow and liquid are compared to find them common characteristic, so traffic flow characteristics are deeply analyzed. Secondly, on the base of knowing traffic flow characteristic, traffic flow compressibility and viscosity models are established by hydrodynamics methods. Traffic flow compressibility model provides a new thinking for traffic wave theory and traffic flow viscosity model offer a new mean to the problem of interference between vehicles and bicycles. So, this thesis contents three parts as follows:The first part is the theory foundation for the thesis, and provides theory support for main content of thesis. For one thing, the main traffic flow characteristics are gained by comparing traffic flow with liquid. For anther thing, essential traffic flow parameters and their relation models are particularly introduced. At last, basal traffic flow theory models and traffic wave models are discussed. To accommodate traffic flow theory of crowd status, improved traffic wave model is also introduced.Firstly, traffic flow's constringent phenomenon is described on road in the second part. According to this, traffic flow compressibility's define is gained and parameters along with its meaning describing this characteristic are conformed. And then, according to hydrodynamics,mach number is brought into the study of traffic flow compressibility, so the formula of traffic flow compression factor and the relation between mach number and liquid parameters is gained. On the base of the knowledge above, traffic flow compressibility model is established. Traffic flow's compression degree is reflected by the traffic compression factor which calculated by the traffic flow compressibility model. According to the concept of compression factor and compression model, a stop wave model is built. The accuracy is improved in some degree compared with the result from traditional stop wave model by validating observed value, so this model can calculate traffic stop wave. Finally, traffic stop wave model is applied to calculating the maximum queue and fastest queue location of bicycles at signalize intersection. Because of obvious compressibility of bicycles at signalize intersection, this method provides a new mean for calculating bicycles'queue length.The third part firstly introduces that traffic flow viscosity study contains traffic flow oneself and mixed traffic flow's interference, and analyzes practical phenomenon as described above. And then, Reynolds number is brought into the study of traffic flow viscosity, so traffic flow viscosity factor which describes traffic flow viscosity characteristic is defined. Thirdly, traffic flow viscosity models that fit different statues is built, so the viscosity power and viscosity factor reflecting traffic flow viscosity are calculated by those models. At last, bicycle group length in the traffic viscosity model is defined in detail, and its calculated means is also introduced which provides data support for traffic flow viscosity model.The last part of thesis is a summarization. It analyzes and sums up the improvement of thesis and puts forward scarcity, then the content and direction in the future is fixed on.The study on traffic flow characteristics and theories in thesis can more discover the law of traffic flow movement and make traffic forecast and analysis into practice, so it provides theory support for making best use of traditional traffic establishment. The interference of mixed traffic flow for especial statues in our country is researched, then it can provide theory support for establishment of separated facility, channelization at signalize intersection and traffic management and control. In this way, traffic flow can run unblocked, so road traffic statue is improved and traffic congestion is relieved.