Study On Macroscopic Fundamental Diagrams Based On Big Data

Urban transportation system not only plays an important role in the convenience life for human beings but also acts as basis for rapid economic growth and social development of major cities.With the rapid growth of car ownership,urban traffic congestion is becoming increasingly serious,which not only hampers the development of the city negatively but also affects the normal life of the residents.Therefore,how to find the traffic congestion quickly and take effective measures timely are an important research topic in the field of contemporary Intelligent Transportation System(ITS).In recent years,with the development of various types of information collection technology being widely used,ITS has entered the era of big data.Compared with the traditional fixed detector technology,the floating vehicle information collection technology features on easy installation and maintenance,high data accuracy and large information quantities.,which enables it has gradually become an important data source of urban traffic state analysis.Based on the Floating Car Data of Beijing,this thesis studies the reconstruction of the actual road network based on Vissim simulation platform,and researches into the Macroscopic Fundamental Diagram(MFD)of Wangjing urban road network in Beijing,and analyzes the existence and existence condition of MFD from microcosmic point of view.Furthermore,the road network is divided into small regions and the data has been analyzed.In this thesis,first of all,the collected actual data is preprocessed.Then,the Wangjing urban road network in Beijing has been reproduced using the Vissim simulation platform.The traffic flow of entire 24 entrances of the road network is obtained by relevant calculation method.The average velocity and time occupancy of each link are obtained by Vissim.The average density,average velocity and average flow rate of the whole network,which can be used to draw the three basic diagrams of MFD,are calculated,and then analysis and summary have been undertaken.Secondly,the average velocity,average density and average flow rate of each link can be calculated by the Vissim simulation.Based on the single link and the grid,the existence of the MFD is analyzed from the microscopic point of view using the Principal Component Analysis(PCA)method,and the number of links and grids is gradually increased,and then the necessary number of relevant links or grids are analyzed to make the MFD clear.At the same time,it is also analyzed the issue of existence of MFD of strip area(road)and whether the structure of the grid have effects on the final MFD.Finally,according to the above conclusions,the WangJing road network area is divided into eight regions for analysis,and then the original eight regions are further merged into four,three and two bigger regions.Then the optimal division of Wangjing road network is obtained by comparing the MFDs of each case.