5. Maintenance and work on signalling installations

The maintenance policy for fixed installations consists of ensuring, at the optimum overall cost over the lifecycle, the safety of traffic and the operational availability of installations, taking into account their projected lifespan.

System failures generate :

• or direct impacts on traffic: these are "technical incidents", most often resulting in a degraded mode of operation. It should be noted that, because of the application of regulatory procedures involving human operators, degraded mode operation entails a reduction in the level of safety. It is therefore important to reduce their occurrence and duration. These failures are therefore treated as a priority by maintenance teams;

• or an inconvenience for the operator: for example, a malfunctioning indicator light on a console or...