The main purpose of this thesis is to examine the vertical stiffness changes that take place on the railway track, analysing their origins and causes, modelling their behaviour, in order to develop analysis methodologies for the design of the infrastructure. Likewise, the elements making up the infrastructure are also analysed, delving into the intrinsic characteristics of the global vertical stiffness as well as the stiffness of each of the constituent elements of the rail type section, on each of the typical sections of the stretch under consideration.