Optimization Research On Railway Route Scheme In High Altitude And Large Elevation Difference Mountain Area Based On GIS And Accessibility

Some valuable railway route schemes need comparing from the aspects of technical economy,engineering geology,construction difficulty and regional political and economic to determine the best one.However,now,the influences of route schemes on the social and economic development of the surrounding areas can not be fully quantified.Some studies show that accessibility is the main manifestation of the impact of transportation on regional social and economic development.Based on this,this paper takes the Sichuan-Tibet Railway as an example,and carries out the following research for the quantitative evaluation of the value of each scheme(the Qamdo Scheme,G318 Scheme)in accessibility.(1)Eight prefecture-level divisions were selected as the research area and they were divided into 1158 researching units.We got the comprehensive sizes of each research unit rby entropy weigh method.(2)With the examples of operating railways,the relationship between train running time and distance was obtained by establishing regression model,and the shortest travel times between each two stations were determine.(3)According to rerevant data,based on the influence by altitude and road development,and the calculation characteristics of cost distance tool in ArcGIS,this paper determine the speed of every road section in research area.(4)In order to prevent connecting between expressway and surrounding area,this paper set expressway buffer.Road with different altitude,speed or longitudinal grade has different traffic cost.Based on these,this paper made the cost master dataset.(5)Through precisely setting values of every station's raster,this paper obtained the time accessibilitily diffusing figure and the differences between the figures of central cities under different railway schemes.Based on several accessibility evaluation index,this paper evaluated the influences to surrounding area by different railway schemes to draw a conclusion.Some conclusions are drawn through calculation and comparison.The Qamdo scheme will further promote the cental cities to radiate and drive the surrounding area,and this is conducive to coordinated urban-rural development.In the view of each central cities'development,except Kangding,the Qamdo scheme provide more advantageous to every city.Through quantitative comparison,this paper recommend the Qamdo scheme.Based on GIS tool,from the perspective of accessibility,we can quantitatively evaluate railway schemes.This method will improve the scientific of scheme comparison of railway lccation.Railway is influenced not only by other railways in network,but also by other transportation way,such as road.Building modern comprehensive transportation system is of great significance.Railway construction and regional development are influenced and promoted by each other.