Study On The Data Gap Characteristics Of Traffic Stream At Urban Expressways

The dissertation is based on the doctorate subject fund of MOE "Study on Theories of Bottleneck Forming, Diffusing and Controlling in Urban Expressway System", the Teaching and Research Award Program for Outstanding Young Teachers in Higher Education Institutions of MOE "Study on Theory of Controlling Urban Expressway System" and the Key Project of National Natural Science Foundation "Research on the principal theoretical model and simulation technique of dynamic traffic management and control in urban network". The paper mainly studies data gap characteristics of traffic stream at urban expressways and application to distinguish traffic states . The full paper is composed of six chapters. The studied emphases are Chapter Three Four and Five.Urban expressway is the artery of the city traffic system, but with the increasing of transportation demand, traffic congestion take place again and again, influencing people's life seriously. Take Beijing to instance, there are traffic congestion often. Currently, one of the method that alleviates congestion is to improve road transportation management, which based on traffic stream characteristic of urban expressway. But there is seldom research production about this. So, this paper carries on a research on data gap characteristics of traffic stream on urban expressway. This paper mainly studies the existence of data gap from traffic flow of urban expressway, analyzes the description index of data gap, calibrates the boundary of the data gap, and advances a distinguish method of traffic state based this characteristic. The result can provide some methods and theories basis for transportation management of urban expressway.There are three basic parameters of traffic flow stream, flow, speed and concentration, concentration have two index: density and occupancy, that include time occupancy and space occupancy. On the variable relation plots, which drawn by data collected from freeway, such as flow-speed plots, flow-occupancy plots, and speed-occupancy plots, data pots cluster into two regions, one represents congestion data, the other represents uncongestion data, and there is a space with sparse data, even no any data, these space can be defined data gap. Usually, when traffic stream transit from uncongestion to congestion or verse, there will be data...