By integrating the merits of the map overlay method and the matrix method, a Geographic Information System (GIS) based map overlay method is developed to analyze comprehensively the environmental vulnerability around road and its impact on the environment, which is adapted for the comprehensive assessment of road environmental impact and the optimal selection of road alignments. The assessment process of the GIS based map overlay method and a detailed case study are presented, which include deciding the system structure and weights of assessment factors, making environmental vulnerability grade maps, calculating the respective coefficients of road impact extent for each factor, and evaluating the alternative alignments comprehensively to obtain the best one. (Author/publisher).
Abstract