The goal is to be able to estimate the damage of a structure with simple vibration tests such as modal analysis. This has been applied to the analysis of the damage state of tunnel railroad blocks for which a test giving the level of damage has been developed and which makes it possible to test each block of a railway track on slab without having to dismantle the track. On the other hand, in partnership with the company Sateba, the concept of smart sleeper measuring the deformations in a railway sleeper when a train passes is being studied. Using the measured signals, this involves estimating the condition of the track and rolling material to optimize maintenance operations. For this, it is possible to estimate the wheel-rail contact forces from the deformations of the sleeper and also estimate the stiffness under the sleeper, or even its evolution over time.