This Technical Specification defines the process, measures and demonstration of safety for the electric traction systems of–railways,–guided mass transport systems,–trolleybus systems.The systems can be elevated, at-grade and underground.It does not apply to–underground mine traction systems,–cranes, transportable platforms and similar transportation equipment on rails, temporary structures (e.g. exhibition structures) in so far as these are not supplied directly or via transformers from the contact line system and are not endangered by the traction power supply system,–suspended cable cars,–funicular railways,–magnetic levitated systems,–railways with inductive power supply without contact system,–railways with buried contact system that is required to be energised only below the train to ensure safety,but it can support the safety considerations of such systems as far as applicable.This Technical Specification refers to standards and common practice to demonstrate safety including the functional aspects.This Technical Specification applies to the erecting of new lines and to all significant changes of existing lines.