In this study, a decision support system for the optimum railway route selection is suggested and an application of this system is presented. To minimize the disadvantages of the conventional Analytical Hierarchy Process (AHP), the Modified Analytical Hierarchy Process (M-AHP), is considered in the present study. For the application of the M-AHP to the railway route selection, Kayas (Ankara, Turkey)-Yerkoy (Yozgat, Turkey) high speed railway project is considered as the application of the study. A total of eight parameters including cost, allowable speed, length of route, number of station and accessibility, amount of the long tunnel, amount of high viaduct, amount of displacement of the existing conventional railway, and amount of nationalization are considered in the medium scale. A total of seven candidate routes are assessed, and the results are presented. The system produces plausible and applicable results and it may provide quick and cheap solutions for railway route selection.