Different requirements for track structures, switches and crossings have recently gained prominence, in part, due to preparations of high-speed lines across the Czech Republic. High-speed turnouts must fulfil many criteria, because the speeds on main line turnouts normally reach between 250 and 350 km/h. The main requirement, which most structural modifications and turnout improvements deal with, is to reduce dynamic load. The PhD thesis aims to research in particular possibilities for reducing dynamic load caused by passing vehicles; primarily by track stiffness optimization by fastening system modifications. The work is based on the observation of a test section in Ústí nad Orlicí railway station, where switches and crossings with modified fastening systems were installed. The evaluation is then used as a basis for designing of a rail fastening system to optimize the track stiffness in high-speed switches and crossings to reduce the dynamic effects.