Developing optimal road alignment using geospatial technologies: A case study from ginchi to chullute, oromia region

Background: Route selection is a critical step in road design and construction, particularly in landslide-prone areas where environmental and economic challenges demand innovative solutions. Geospatial technology provides a robust framework for optimal route planning by integrating various decision-support tools. Although global research has extensively addressed route optimisation, limited studies have focused on landslide-prone areas in Ethiopia, highlighting a gap in the application of advanced geospatial techniques in such regions.Objective: This study aimed to develop an optimal road alignment connecting Ginchi to Chullute in the Oromia Region by employing geospatial tools to address engineering, environmental, and landslide-related challenges.Methods: The study incorporated Sentinel 2A satellite imagery, ALOS DEM, geological maps, population data, SPOT 5 imagery, and field visits to identify key alignment factors. The Analytical Hierarchy Process (AHP) was used to assign weights to factors, generating engineering, environmental, and landslide cost surfaces. A hybrid cost surface, integrating these factors with equal weighting, was developed for least-cost path modelling using GIS tools. Landslide susceptibility was assessed using the Frequency Ratio Method, and the model’s accuracy was validated with an AUC score of 0.756.Results: The hybrid least-cost path was identified as the optimal route, reducing the existing road length from 122 km to 103.46 km. Compared to other modelled paths (104.3, 105, and 98.3 km), the proposed route was less susceptible to landslides and more feasible from an engineering perspective.Conclusion: This study highlights the effectiveness of integrating geospatial tools for environmentally sustainable and cost-efficient road planning. These methods can also be extended to the design of other linear infrastructures, including drainage, pipelines, and railways.