A three-dimensional model for soil-transportation structures is presented. This model exploits the geometrical periodicity of the system and takes into account the dynamic soil–structure interaction with a methodology coupling a boundary element method for the soil and a finite element formulation for the structure. A general overview of this approach is given based on several real transportation structures. Moreover, comparative studies between the different structures have been carried out. Then the model is improved by introducing a general rule for the determination of the optimal number of cells. Finally, the periodic modes propagation is investigated offering a first seizing of the significant dynamical phenomena in the soil–structure system.