Railway axles are safety-critical components whose failure could result in large additional costs for the infrastructure manager and the railway operator and, in most serious cases, even lead to unacceptable human losses. For this reason, they are periodically inspected by means of non-destructive techniques usually requiring expensive service interruptions. Considering the special case of solid axles for freight cars, this paper investigates the feasibility to apply two structural health monitoring (SHM) techniques to increase vehicle safety and reliability and, at the same time, to decrease the costs of damage inspection. In particular, the considered SHM techniques are Acoustic Emission and the measurement of low frequency vibrations. In...