Evaluation of Optimal Ghat Road Alignment integrating Engineering, Environmental and Landslide Parameters using Geospatial Analysis

Roads in a hilly region contribute to significant development of the area and may cause negative impacts on the fragile environment. Optimal road alignment in the hilly region is challenging and mandates geospatial analysis that involves topographic and environmental parameters like slope, soil stability, forest cutting and obstruction to drainage. In this study, a multi-objective approach is proposed to delineate optimal road alignment in the hilly region of Sathuragiri hills, India using Geographic Information System (GIS) based integration techniques. Analytical Hierarchy Process (AHP) was used to generate suitability surfaces based on Engineering, Environmental, Landslide and Hybrid approaches. Thematic information like geology, land use, drainage network, slope, aspect, soil texture, distance from the road etc. have been generated from Remote Sensing and Collateral datasets. The suitability surfaces were generated through standardization and integration of criteria using a weighted overlay approach in the GIS environment. Alternate alignments were generated with these suitability surfaces using Dijkstra Algorithm for finding the shortest cost path. These alignments were evaluated for critical parameters like length of road, no. of bridges/culverts, area of forest cutting, area of agriculture land affected, length of road in critical slopes. The results indicate the efficiency of the hybrid approach combining the engineering, environmental and landslide risk-based parameters in the alignment planning.