Road Alignment Optimization in Landslide-Prone Areas: A GIS-Based Approach in Yatiyanthota, Sri Lanka

This study focuses on road alignment optimization in a hilly region of Sri Lanka, specifically the Yatiyanthota and Yatiyanthota town areas, which are prone to landslides. This research aims to use GIS techniques to optimize the road alignment design for a proposed bypass road in the area, taking into account economic, environmental, and societal factors. Traditionally, engineers have used manual drafting techniques to design road alignments, but this method has limitations, particularly in considering multiple spatial factors simultaneously. Therefore, GIS techniques, such as the Least Cost Path algorithm in ESRI's ArcGIS, are used to generate optimal alignment alternatives for the bypass road. The study compares and assesses the optimal alignment alternatives in order to bypass landslide-prone areas in Yatiyanthota, which was considered several factors simultaneously. The results show that the least cost optimal alignment coincides with the engineering factors than all other assessment criteria. Additionally, the optimal alignment is shorter, and the cut/fill cost is reduced compared to the existing alignment. This research provides valuable insights into using GIS techniques to optimize road alignment design in hilly regions with complex geography and geology prone to landslides and earthquakes, with implications for road development projects in Sri Lanka and other similar regions.