Research On Optimal Selection Of Railway Route Scheme Based On Environmental Location Design In Western Mountainous Area

Most region of western China is mountainous, accompanied by complex terrain condition and terrible topographic undulation. Building a railway in these regions is difficult because of the need to overcome large elevation difference and terrain obstacles. As a result, nearly all railway projects in western mountainous area have large engineering amount and high proportion of bridge and tunnel in lines. So in traditional railway route planning, the major concern is technical and economic factors because of the limited investment, while the impact from railway construction to external environment is considered as a subordinate factor.Building a railway in western mountainous area may have great negative impacts on the environment, especially on the ecological fragile zone and environmentally sensitive areas. So the concept of environmental protection must be applying in railway route selection, implementing environmental route selection. In addition, the western region lags behind in economic and social development. How to better play the role of railway in promoting the economic and social development need to be considered in the railway route selection process.This paper summarizes the current research results of environmental railway alignment selection after analyzing the influence of railway construction on the social and natural environment. Then according to the theory and methods of comprehensive evaluation, combine with features of the western mountainous region, the paper has established an indicator system containing environmental impacts in order to evaluate the railway route schemes.First, after conducts a comprehensive study on the factors which need to be considered in environmental railway route selection, this paper put forward that social and economic impacts also need to be involved in the process apart from natural environment effects. Then put up the requirement and principle of railway location design after analyzing the environmental problems encountered in the process of railway construction before. Furthermore, the paper summarizes the methods and specific steps of environmental railway location based on the study of environmental impact assessment, environmental economics and techniques of railway location.Then, in accordance with the principles of indicator system establishment and using target decomposition method, the railway route schemes evaluation index system was established from the aspects of natural environment, social environment, technique and economics based on comprehensive analysis of railway and the outside environment. In order to facilitate the evaluation of railway route schemes, the indexes were quantified by statistical analysis, threshold method and expert scoring method.Finally, after analyzing a variety of comprehensive evaluation method, fuzzy synthetic evaluation and artificial neural network evaluation method were selected to build assessment model because of their characteristics and applicability. On the basis of this, the evaluation models are applied in a typical engineering case of railway line selection in the western mountainous area. The results shows that the two evaluation models established in this paper have feasibility and practical value in railway route schemes sorting. However, the artificial neural network method is better for the evaluation of railway route scheme after comparing the calculation process and evaluation results of the two methods.