Optimal high-speed rail route selection using GIS, remote sensing, and multi-criteria decision analysis techniques

High-speed rails (HSR) are the most efficient mode of transportation from the perspective of travel time reduction, low travel costs, time-saving, and environment. The HSR route selection is an essential and complex process that involves several factors that must be considered. The integration of geographical information system (GIS) and remote sensing (RS) with multi-criteria decision analysis (MCDA) techniques has been used in different routing problems such as roads, railways, and HSR. In this study, a GIS-based MCDA method was adopted to generate the optimal HSR route between Kabul and Kandahar cities in Afghanistan. The influential factors on the HSR route location and their relative importance were determined by questionaries performed by transportation sector experts and the fuzzy analytical hierarchy process (fuzzy-AHP) and analytical hierarchy process (AHP) MCDA methods were employed to calculate their weights. Slope, land use/landcover (LULC), soil types, distance from rivers, proximity to roads, proximity to towns/cities, landslide risk, snow avalanche risk, flood risk, distance from faultlines were considered as the influential factors on the HSR route location selection. Separate analyses were performed for deriving the landslide, snow avalanche, and flood susceptibility layers/maps. The fuzzy-AHP method was utilized to calculate the weights and relative importance of the factors considered in a landslide, snow avalanche, and flood susceptibility assessments. The results showed that the methodology adopted in this study successfully generated the optimal HSR route that is geometrically the shortest, economically feasible, safest in terms of natural disaster risk, and functionally with a wide-range service area. The route has a 502 km length, connecting 3 adjacent cities with Kabul and Kandahar cities. About 470.05 km of the route has a slope of less than 4%, while 30.35 km and 1.93 km have 4-10% and more than 10%, respectively. The results of the study will enable transportation planners to conduct a detailed investigation in the field using the HSR suitability map and conduct a topographical survey around the generated route for determining the centerline of the route. Furthermore, the results can be a good source of information for landuse planners for land readjustment and future landuse development.