Research On Reachability And Fractal Characteristics Of Urban Transportation Network Based On GIS

Transportation network is the basis of regional economic and cultural exchanges,and its development has been widely concerned.Accessibility is an important index to evaluate the transportationnetwork,which generally refers to the convenience of a point in the transportationnetwork system to reach other destinations.With the continuous development of GIS technology,the process of reachability calculation and result analysis require more and more intuitive,quantitative and effective spatial expression.The combination of GIS technology and accessibility evaluation model provides an effective technical means for these studies.On the other hand,the internal structure characteristics,spatial distribution pattern and other spatial form characteristics of regional transportation network are the internal factors that affect the development of regional transportation network.Based on the fractal theory,the fractal measurement model of regional transportation network space is constructed,and the development characteristics of regional transportationnetwork space are quantitatively described,which can not only reveal the reasons for the current situation of transportation accessibility development to a certain extent,but also help to recognize the spatial characteristics of regional transportation network development from a rigorous mathematical level,so as to provide a more scientific and comprehensive decision reference for the optimization layout and plan＿mading of an regional transportation network.Therefore,based on the needs and requirements of regional transportation network research,using fractal theory and complex network theory,and supported by GIS technology,this paper systematically studies the technical process and measurement model of transportation network accessibility evaluation and fractal feature measurement,and applies it to the quantitative analysis of Nanjing transportation network spatial form.Firstly,the paper summarizes the basic connotation of accessibility evaluation model and fractal theory commonly used in transportation network,and then expounds the advantages of GIS technology in accessibility evaluation and fractal measurement and calculation.After comparing the advantages and disadvantages of commonly used accessibility evaluation model and combining the technical advantages of GIS,the paper puts forward the accessibility evaluation model based on the shortest travel time and transportation distance In line with the actual level of transportation accessibility.Secondly,based on the significant advantages of GIS technology in spatial data collection,spatial analysis and network model construction,the technical process and spatial fractal measurement model of transportation accessibility evaluation based on GIS are established,including evaluation index selection,data collection and processing,construction of accessibility evaluation model,calculation and processing of accessibility value,comprehensive evaluation of accessibility and the calculation of space fractal dimension.Finally,taking the main urban area of Nanjing as an example,the paper calculates,analyzes and visualizes the accessibility and spatial analysis characteristics of the transportation network in the study area by using the above-mentioned relevant method models,and puts forward optimization suggestions according to the problems existing in the accessibility and spatial structure characteristics of the transportation network in the study area.