An increase in train speed generates amplified track deflection. With higher speed, larger strains are induced within the track and subgrade structures. This results in nonlinear behaviour of material properties, particularly the soil stiffness. In railway engineering, it is challenging to deal with these high levels of amplification because the deep wave propagation within the track and underlying soil structures is complicated. Therefore, this paper investigates the influential variables that cause a significant impact on the dynamic amplification of the railway. Four modelling strategies used to generate findings into the problems of railway track dynamics and track-soil nonlinearity. The four types of model are analytical, combined analytical–numerical, 2.5D finite element and 3D finite element. These four models are used to analyse the cases of homogenous half-space soils, homogenous soils above bedrock, layered soils, low-stiffness soil layers and track-soil nonlinearity. The analysis results provide a better understanding of wave propagation characteristics within the subgrade structures. This can be useful for consideration of the design or improvement of railway track structures and earthworks.