Structures of rail vehicles are designed for a useful structural life of 30 years. However, structural problems which reduce the mechanical performance of the structure might appear due to normal operation conditions and, in some cases, make it unsuitable for a safe operation. This document presents the structural diagnosis of a metro system and the method for the redesign of structural elements of rail vehicles that was derived from this diagnosis, so that the structural performance of both the element and the whole structure is improved. It is based on the European standards related with aluminium and railway applications, and considers the necessary aspects to produce a safe solution for the final design.