This book proposes a method for the simulation of the dynamic interaction between vehicle and railway track. The model has been designed to take into account the complexity of wheel−rail contact, railpad and ballast, with low computational requirements. A modal description of the rails and the sleepers is presented, imposing the cou- pling between these elements and the vehicle by means of the associated interaction forces. This provides a model with a reduced number of coordinates and therefore a low computational cost is achieved. It is shown that this model also enables to incorporate the associated nonlinear characteristics between the different elements by means of a simple formulation. In the development of the following work several commercial softwares have been used in order to obtain a final program in a modular and user-friendly perspective.