Models (IMAGE) CNRS Caption Amplitude of the displacement field after a train passes on the track. The left-hand figure corresponds to a simulation with homogeneous ballast and the right-hand image to a simulation with heterogeneous ballast. Credit Lucio de Abreu Corrêa, Laboratoire de Mécanique des Sols, Structures et Matériaux (CNRS/CentraleSupélec) Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.