In the last few years, different numerical models for the study of railwayvibrations in tunnels have been developed. Virtually all of them assumean elastic and linear behaviour of the soil. In this article the influenceof soil constitutive model is investigated, comparing an “advanced”model of the soil called Hardening Soil model with small-strain stiffness(HSsmall) and the Mohr-Coulomb (MC) model. Moreover, the influenceof soil stiffness has been studied when this is considered in the rangeof small strains (E50) or in the range of very small strains (E0). Thesemodels have been applied to a real case through a 2D finite elementmodel formulated in the time domain, where it is concluded that bothsoil stiffness and the amplitude of the maximum tangential strain arethe most important geotechnical parameters when estimating thedeformational parameters and the constitutive models of the soil mostadequate for the study of railway vibrations in tunnels.