ABSTRACT
The deformations, displacements, and accelerations at the decks of railway bridges which affect the installed track are serviceability limit states for the bridge, but correspond to ultimate limit states for the track and for the circulating vehicles, as these affect their safety. The engineers dedicated to the design and concept, execution and exploration of railway bridges
should not forget at any moment that the bridge must support another structure: the track (with or without ballast), to which the loads acting on the bridge are transmitted and which conditions for its correct and safe functioning have to be assured at all times.
