Over the past years, population growth has become a major challenge in developing countries. The starting point of this challenge is the resulting volume of urban traffic leading to increased time, demand and public transport costs. As a result, the purpose of this study is to use spatial analysis and the ability to represent three-dimensional analysis of geographical information system (GIS) to locate the construction of high-speed rails. Basically, the selection of high-speed railways is an exploratory process involving a diverse set of conditions and choices. Therefore, experts and professionals based on their knowledge use different criteria to solve decision problems. Criteria used in this study include proximity to the Nasiriyah and Najaf, slope, user maps, proximity to settlements, access to roads, water resources and the status of oil transmission lines. First, the data were analyzed in two separate steps using the multi-criteria decision model (MCDM). At the same time, the analytic hierarchy process (AHP) has been used to weight each criterion, and a new technique has been proposed to prioritize routes based on the technique for order of preference by similarity to ideal solution (TOPSIS) method for single-rail trains. Then, by overlapping the weighted layers of the optimal paths, the best paths were categorized into five categories including "very appropriate", "appropriate", "moderate", "inappropriate" and "very inappropriate". The results proved that the length of the selected optimal route from Nasiriyah to Najaf is exactly 224 km.

High-Speed railway; Geographical Information System (GIS); Routing, Railway; Multi-criteria decision model (MCDM)