Research On The Auxiliary Decision Support System Of Railway Alignment Based On GIS

The digital railway alignment is a new field that related to multidisciplinary and much professional knowledge, the support of informational surveying, virtual reality technology and computer simulation is necessary for further development. The route selection based on BIM, 3D geographical environment modeling and the alignment intelligent selection have always become the hot research area in recent years. At present, the route selection is getting in touch closely with the developments of computer and modern measuring technology. In this respect, great progress has been made in the research of route selection that based on GIS(Geographic Information System). But when determine the alignment, it will be affected by the subjective factors from the engineers, and there are few mature software used to generate the right alignment automatically so far.Combined with the powerful ability of data process and spatial analysis in the GIS software, this paper has developed the decision support system of railway alignment based on GIS by using the data management and spatial analysis tools in Arc GIS.The main research contents and results are as follows:(1) The research has built the hierarchical analysis model based on GIS of the railway to the auxiliary decision-making. According to the selecting principle of the railway to the impact factors, the research classified the impact factors of the route selection, building for the decision hierarchy analysis model applied for the line of the cost of grid data, and giving the weight value of each layer in the model according to the hierarchical method and the expert investigation method.(2) The research created cost of raster data including related line selection factors. We carried on the vector lattice, raster data assignment and the cost of raster superimposed through the date of the geographic database in Arc GIS. The research took influence factors into account during the decision-making process of line selection, through keep decision hierarchy analysis model of impact factors according to their corresponding weights on top of the comprehensive cost of grid data set.(3) The research realized the selection of the line direction in Arc GIS. The research calculated cost of raster data set using cost distance algorithm and back link algorithm in Arc GIS, and generated least cost path between the starting point and the target point, realizing the selection of the line route between two points.(4) The research developed the auxiliary decision system of railway alignment based on GIS. The auxiliary decision system of railway alignment conducted second development about Arc GIS based on C#.NET, SQL Server 2008 and Arc GIS Engine10.2. This system has the nice and convenient operating interface, it can be used for considering every influence factors of route selection synthetically and generating the right alignment automatically. According to project cases, the auxiliary decision system is especially suitable for route selection in the feasibility research stage or pre- feasibility research stage, it can determine a globally optimal alignment. Using this system can dramatically improve the efficiency of railway route selection.