Structure Analysis Of Urban Road Network Based On The Methods Of Centrality Measure And Community Structure Division

Urban road network is an important part of urban system,and its structure has an important impact on urban traffic operation.Under the background that the problem of urban traffic congestion is becoming more and more serious at present,in order to solve the problem of urban traffic,the first step is to understand the structure of urban road network.Most of the traditional studies only make a brief analysis of the form of urban road network.The research methods used lay particular emphasis on qualitative description and lack of deep-seated research on the structural characteristics of road network.It is urgent to introduce new theories and methods.The method carries out more detailed research and Analysis on the spatial structure of urban road network.In recent years,the study of complex network has attracted the attention of scholars.,and some achievements have been made in the study of its characteristics.The existing research has proved that road network is a typical complex network.It provides a new way to study the structure of urban road network.Based on the theories and methods of complex network,this study selected Beijing,Chengdu,Nanjing and Wuhan as the research area,and used high-resolution satellite images and some road data to construct the urban road network data set of the research area.Computing the centrality indexes such as Betweenness,Straightness,Closeness of the urban road network in the study area,and analysis their spatial distribution characteristics and numerical statistical characteristics based on the urban road network data set.And then,identifying the community structure of the urban road network in the study area with GN algorithm,and analysis the distribution characteristics and morphological characteristics of the road network communities.Finding the characteristics of crowd activities in the study area by the heat-map data,the POI data and real-time traffic congestion data,and analyze the correlation between road network structure and crowd activities.Finally,summarizing the structural characteristics of urban road network and to point out the structural differences of different types of road networks.The main contents of this study include:(1)This study calculates some centrality indexes of urban road network nodes in the study area.The calculation results show that the centrality of road network has distribution characteristics,higher Betweenness sections are not completely distributed in the central area of the road network.The numerical distribution of the Betweenness has the characteristics of power distribution,and Straightness distribution has obvious regional differences.The main roads,urban ring roads and bridges across rivers all have high centrality.By comparing the centrality with the actual road condition,it is found that the Betweenness could describe the importance of road network nodes in road traffic.(2)This study introduces the method of community structure identification,and explores the differences in the spatial structure of urban road network on the basis of previous studies.It is found that urban road network has remarkable community characteristics.The larger the scale of road network,the more the number of communities divided,but the relationship between them is disproportionate.The form of road network will also affect the structure of community.The more compact the associations are,the more regular their distribution is,the smaller the difference in the size of the associations is.(3)This study uses new data that can reflect the status of human activities to analyze the relationship between road network structure and human activities,and tries to analyze the urban spatial pattern of the study area from a new perspective.The results show that the human activity is high in the central area of the city,the road radiation capacity of the central area has a greater impact on the traffic efficiency,and the influence of road network structure on the human activity is not prominent.(4)The study finds that the road network of different cities has distinct characteristics.Beijing road network is large but not compact.Traffic flow is concentrated on the main road,and the role of the ring road in the road network is very prominent;Chengdu road network is very close,the radiation capacity of the road network from the center to the outside is very strong,and the role of urban ring roads and scattered trunk roads in road network is very prominent;Nanjing road network is obviously separated.The development axis of "Y" type of city is very obvious,and the centrality of the main roads in the north-south direction of the city is prominent.;Wuhan road network has a multi-center features,the connecting effect of key sections is remarkable,but the overall road network center is not high.