Abstract: The rapid development of large-scale transportation infrastructure exacerbates ecological risks, especially the construction of highways in ecologically fragile areas, which are prone to pose a major threat to biodiversity and ecosystems along the routes. There is still a lack of universal research on how to better optimize the selection of highways. To bridge this gap, by constructing an ecological sensitivity evaluation system for highways and using hierarchical analysis (AHP) and ArcGIS spatially weighted overlay analysis to guide the optimization of its selection in ecologically fragile areas, further fragmentation and loss of ecosystems can be effectively prevented. 1) Nine indexes: elevation (B1), slope (B2), aspect (B3), water source protection (B4), land use status (B5), Scenic resources protection (B6), vegetation coverage (B7), landscape fragmentation (B8), and geological hazard (B9) were evaluated, and the weight values were B7> B1> B4> B8> B5> B2> B9> B6>B3, indicating that vegetation cover contributed most to the ecological sensitivity of highways, while aspect played a relatively small role. 2)The ecological sensitivity score of Yuping-Zhenyuan highway was between 1.60 and 5.62, with 10.72% and 25.84% of the highly sensitive and moderately sensitive areas, respectively. 3) Comparing indicators of traditional road alignment (B line) with ecological sensitivity based alignment (K line), the ecological sensitivity of K line (4.34) was lower than B line (4.58), suitability of engineering construction and ecological restoration strategies for different road sections were proposed. This study provides a scientific basis for highway alignment selection and can be extended to planning and practice of green infrastructure in other fields.

Key words: ecological sensitivity, evaluation system, optimization of highway alignment, ecologically fragile areas, analytic hierarchy process (AHP), eastern mountainous areas of Guizhou, China