The optimization of maintenance strategies has become a key issue in the railway industry but also in most industrial fields. To address this challenge, many studies dealt with the estimation of optimal maintenance parameters. But what commonly happens when the degradation process suddenly changes? The operator has to face an unexpected, increasing number of severe defects (and then a strong drop of its availability). These changes are generally due to either: a new component, introduced in the system for obsolescence reasons; or changing operating conditions. Based on the dynamic Bayesian networks (DBN), formalism that has been proved relevant to perform reliability analysis can easily represent complex system behaviors. This paper introduces a dynamic maintenance strategy, able to detect these drifts and to evaluate their impacts on the rolling stock doors system’s behavior.