Efficient transportation networks are essential for ensuring connectivity and accessibility. With increasing population and urbanization, the demand for well-planned transportation routes continues to rise. In mountainous regions, determining the optimal alignment for transportation routes is particularly challenging due to complex terrain and multiple influencing factors. This paper aims to identify the critical factors influencing route selection for transportation infrastructure in such regions. A thorough review of existing literature was conducted to identify and compile a comprehensive list of factors that influence route planning. The analytic hierarchy process (AHP) was applied to determine their comparative significance, with slope identified as the most critical factor, followed by elevation, land cover, and aspect. A GIS-based methodology was developed to integrate these factors, utilizing Dijkstra’s algorithm to determine the most efficient route. The proposed approach was validated through a case study, demonstrating its effectiveness in selecting an optimal transportation corridor with minimal environmental impact and improved accessibility.