This article deals with the gains on safety and availability of rail systems for an integrated company. The RATP gathers railway operating, maintenance and engineering activities. To maximize the benefit it can take part of this situation, the RATP adopted an integrated engineering. In a first part, this article describes the organisation of the RATP as an integrated company, then it presents the advantages of this organisation on availability and safety in the project life cycle, and finally it presents the rolling stock example in the middle of the integrated engineering interfaces and the benefits provided by the integrated company.
