Research On Calculation Model Of Subway Network Scale Based On Urban Development

The total amount control of subway network scale is an important work in the network planning stage,which is related to the orderly construction and sustainable development of urban rail transit.Unreasonable planning of network scale will bring huge risks and losses,which will lead to the premature occupation of a large number of urban resources and the increase of government financial pressure;Too small can not well meet the needs of urban development,resulting in the deterioration of urban traffic conditions and restricting urban social and economic development.Due to the diversity,complexity and uncertainty of influencing factors,at present,the central line network scale in engineering practice still adopts the method of single factor estimation and then qualitative comprehensive analysis.The factors considered are more one-sided and the results have more subjective components.This paper attempts to establish a quantitative calculation model of subway network scale based on the characteristic index of urban development from the perspective of the coordination between subway network scale and the development degree of urban central area.Based on the analysis of the factors affecting the scale of subway network from the perspective of urban development,this paper puts forward an index system to measure the degree of urban development,constructs the urban comprehensive development index with the panel data entropy weight method,and establishes the BP neural network calculation model of subway network scale based on Urban development.The main research contents and results are as follows:(1)The adaptability between subway and urban development is analyzed.Based on the study of the general law of urban development,the ideal growth curve of subway network scale is obtained by fitting the collected subway network development data of 7cities at home and abroad with logistic function,and the development law of subway network scale is revealed.(2)Based on the analysis of the factors affecting the scale of subway network,an index system to measure urban development is constructed.Taking the interactive development process of Tokyo Metro and the city as an example,this paper analyzes the action mechanism between urban development and the scale of subway network from four aspects: traffic demand,basic scale,economic strength and planning policy,and obtains 10 key factors affecting the scale of subway network by using the interpretive structure model method.On this basis,11 urban development research indicators are selected by using the correlation analysis method.(3)Put forward the urban development index.Based on the panel data entropy weight method,this paper establishes the calculation model of urban development index,determines the weight of each index,collects the urban development index data of 10 cities in China for 17 years for empirical analysis,and calculates the development index of each city in different years.The results show that the urban development index can significantly reflect the law of urban development,and prove that there is an analytical correlation between the degree of urban development and the scale of network,which lays a foundation for establishing the calculation model of line network scale.(4)The BP neural network calculation model of subway network scale based on urban development is established.Based on the panel data,the polynomial individual fixed effect regression model is established,and the quantitative relationship between the network scale and urban development is obtained.The panel data is introduced into BP neural network,the training set and test set are set,the adaptive gradient descent method is used for network training,and the cross validation method is used to minimize the error function.After many network training,the structure and parameters of BP neural network are determined,and finally the calculation model is established.After the verification of the test set,the effect of BP neural network calculation model is better.(5)Taking Qingdao subway network as an example,the calculation model is verified and analyzed.The subway network scale and urban development index of Qingdao from 2015 to 2020 are calculated and compared with the results of traditional methods.The results show that the model established in this paper has higher accuracy and precision,and has better dynamic adaptability to the level of urban development,so it has certain application value.The research results of this paper provide a quantitative calculation model of subway network scale based on the characteristic index of urban development degree for urban rail transit network planners,which is conducive to the dynamic coordination between subway network scale and urban development stage,improves the theory and technology of network planning,and is of positive significance to the scientific development of network planning.