Method Of Node Importance Measurement In Urban Road Network

The node importance measurement plays an important role in analyzing the reliability of the urban road network.Centrality index in the context of sociology is frequently used to measure node importance in urban road network.However,researchers only take into account the network topology structure with centrality index for node importance,without considering the geographical information and traffic flow characteristics of the urban road network.In this thesis,the topological structure,geographic information and traffic flow characteristics of urban road network are all considered,and methods of node importance measurement of urban road network are proposed based on a spatially weighted degree model,the Hansen Index and h-index from different perspectives.Experiments are given to show the efficiency and practicability of the proposed methods.In this thesis,the research contents and conclusions are as follows:(1)A method for node importance measurement based on an improved spatially weighted degree model is proposed.Taking into consideration the geographical aspects of urban road network,an improved spatially weighted degree(ISWD)model is proposed for node importance measurement in urban road network in which the functional class,the length and the number of network links are considered to be important factors for determining the node degrees of urban road network.A weight coefficient is used in this new model to account for the contribution of each factor to the node degree.The proposed model is compared with several node degree models in the results analysis of a simple road network.Experiment results ind:icate that the improved spatially weighted degree model obtain better results than other node degree models.In addition,the model is with high computational efficiency and can be used in large networks.(2)A method for node importance measurement based on accessibility is proposed.A method for node importance measurement in urban road network based on the Hansen Index is proposed in which the traffic flow and the reciprocal of shortest paths between nodes are used as the attractiveness and the impedance function.The proposed model is compared with several different centrality measures in the results analysis of a simple road network.Experiment results indicate that the Hansen Index has a better capability in identifying critical nodes of urban road network than other topology-based measures.(3)A method for node importance measurement based on h-index is proposed.Taking into consideration the spatial correlation of traffic flow of intersections,a method for node importance measurement in urban road network based on h-index is proposed.The proposed model is compared with several different centrality measures and traffic volume measure in the results analysis of a road network.Experiment results show that the proposed method gives consideration to both the number of nodes in network and the influence of the nodes,and topological features and traffic characteristics of road network are reflected by only one index.The method has a better adaptability than a single index in practical application.