Research On The Extended Length Of Urban Rail Transit Line

The spatial structure of Chinese cities is changing from single center mode to group development mode.In order to make the urban rail transit better serve the residents in each cluster area,more and more regions choose to extend the existing rail transit to surrounding clusters.However,the extension line is different from other newly constructed rail transit lines.The increment of passenger flow caused by the extension line may impact the passenger flow of the existing line and even affect the normal operation of the whole line.Therefore,it is particularly important to reasonably set the extension length of urban rail transit lines.In order to promote the axial development of urban spatial structure and promote the urban construction and economic development along the rail transit,this paper studies the reasonable extension length of urban rail transit lines.This paper first analyzes the evolution of urban spatial structure at home and abroad and summarizes the overall trend of urban spatial structure evolution.This paper expounds the relationship between urban rail transit and urban spatial structure,and puts forward the function of urban rail transit extension line in the development process of urban spatial structure and the limitation of extension line in the planning and construction process.Secondly,the basic rules of the influence of the extension line on the existing passenger flow are summarized from three aspects of the time distribution and spatial distribution of passenger flow across the line.Taking xi 'an metro line 2 as an example,this paper verifies the accuracy of this rule,and provides a basis for determining the reasonable extension length of the following lines.Thirdly,this paper determines the basic interval and station location of the line's extendable length by analyzing the construction factors such as the length of the extension line and station selection?Taking the longest length of the interval as the initial length,a passenger flow prediction model of section based on BP neural network is established.In combination with the idea of proof by contradiction,the paper puts forward an extension length determination method based on the impact constraint of passenger flow in section to judge whether the passenger flow causes too much impact on the existing lines after the extension.If the passenger flow impact is too large,the extension length of the line will be shortened and the passenger flow prediction and impact constraint judgment will be conducted again until the passenger flow impact brought by the line extension is within the controllable range.At this point,the reasonable length of the line can be extended.Finally,taking xi 'an metro line 2 as an example,the reasonable length of the south extension of the line is proposed by using the above method.