Superstructure System Selection for High-Speed Railway Tracks Considering Geotechnical Aspects: A Case Study

A decision-making model for high-speed railway track superstructure selection was developed in this paper. This model first evaluates the technical requirements for system selection, which leads directly to the choice of a specific alternative (ballasted or ballast-less) called "Initial System Selection." In this study, "differential settlement," "embankment height," and "ballast flight" were found to be the most critical technical limitations. In the second step, which is called "Complementary System Selection," the results of the life cycle cost analyses were used for the selection of the complementary parts along the rail route as a function of inflation rate and discount rate. Since the frequent superstructure type replacement along the route causes problems related to maintenance and repair, it was tried to integrate the type of superstructure into the entire route by imposing an engineering judgment. In this case, the next step, known as "Final System Selection," was established to effectively reduce the number of transition zones. In order to demonstrate the applicability of the developed model, the superstructure system selection was conducted for the Tehran-Qom-Isfahan high-speed railway in Iran.