Assessment Of Intra-Urban Spatial Network Structure Based On Spatial Connection Relationship With Taxi Trajectory Data

In the mobile information era,human movement flow,logistics flow,information flow,capital flow and flows in other forms have been moving rapidly in the global and regional scope.Consequently,space and time are compressed,with the connotation of spatial relations and its measurement standards reshaped.In describing spatial relationships,the significance of physical proximity is weakened,while the importance of connectivity is gradually rising.The cognitive perspective of space also changes from physical to social,relationship and network structure.From the perspective of flow space,the development of regional spatial system has demonstrated a trend towards network.Nodes that play a dominant role in the network,instead of the center formed by the location space based on the distribution of developing elements,become the key to the development of the region.In this paper,the theory of intra-urban spatial structure,the research of spatial connection and network analysis methods are summarized.Researches on intra-urban spatial structure is mainly based on empirical research of classical theory.The main theoretical models include single-center model and multi-center model.The study of spatial linkages includes economic linkages,transportation linkages,cultural linkages and comprehensive linkages.Network analysis has been widely used in the study of regional spatial system.However,there is a lack of research on fine-grained spatial scales within cities,consequently,it is difficult to link up with the planning practice of corresponding scales.Therefore,combined with the new data,starting from the fine-grained spatial scale of intra-urban,introducing the analysis method of complex network to identify the structural characteristics of intra-urban spatial connection network has certain practical significance for understanding the development status and mode of intra-urban space and guiding the optimization of urban spatial structure.Wuhu City,Anhui province is taken as the research area in this study.Taxi trajectory data is adopted to represent the flow of people,quantifing the spatial relationship within the city.The stability and applicability of taxi trajectory data to characterize the fine-grained spatial connection structure of cities are verified by identifying the spatial and temporal characteristics of residents’ travel behavior based on the spatial-temporal information contained by taxi trajectory data.Furthermore,grid method is used to divide the intra-urban space into subspace units.The spatial unit is abstracted into nodes and the spatial connection represented by human flow is abstracted into edges to construct the spatial connection network system.By introducing the analysis index of complex network,the evaluation index system of structural characteristics of urban spatial connection network is constructed.Combining with mathematical statistics and spatial analysis,the spatial connection intensity,spatial centrality and spatial network structural characteristics are quantitatively analyzed.The results show that:(1)Taxi trajectory data are suitable for revealing small-scale spatial relationships in cities.Taxi travel data demonstrate relatively stable spatial and temporal characteristics of human transporting.Different travel days show similar fluctuation trend in total travel volume per hour.The average travel distance and duration are short,which can reflect the small-scale spatial interaction.The order of travel volume in different urban areas is the same as that of consumption and fiscal revenue in urban areas.(2)The space with high traffic impact shows relevant importance in the network structure.There is a strong positive correlation between different centrality indices,showing a significant positive spatial agglomeration;(3)The central city of Wuhu presents a single-center,multi-group structure,featuring weak cross-river links.The distribution of human flow and spatial connection is slightly uneven,with a high degree of centrality and obvious polarization.The central city of Wuhu has not yet formed a sub-center with weak cross-river linkages,and the main spatial linkages occur on the East Bank of the Yangtze River;(4)The intensity of spatial linkages is affected by many factors,such as spatial distance,administrative divisions,barriers to land objects,and spatial function.The intensity of spatial connection is weakly negatively correlated with spatial distance.The closely connected nodes in the network are mapped into relatively adjacent spatial groups in space,which overlap with the boundary of administrative divisions,water bodies and other objects locally.At the same time,there are long-distance "capture" and "infiltration" phenomena.The sensitivity of functional space of specific function to distance is low.Finally,based on the urban spatial planning objectives of Wuhu,combined with the results of quantitative analysis of spatial structure,the existing problems are put forward,and combined with the qualitative analysis results of the relationship between spatial network structure characteristics and site attributes,some suggestions on the optimization of spatial structure,such as center cultivation and river-crossing development,are put forward.The whole thesis contains about 53000 words,60 pictures and charts.