This document specifies the general safety requirements for demountable machines and trailers, including road-rail trailers henceforward referred to as machines, for use when travelling and working on railway track. NOTE Trailers, including road-rail trailers, are considered as machines because they are moved along the track by powered machines. This document specifies the requirements to deal with the common hazards presented by their use on the railway during transport, assembly and installation, commissioning, travelling and working on track, use including setting, programming, and process changeover, operation, cleaning, fault finding, maintenance and de-commissioning of the machines and associated equipment when they are used as intended and under conditions of misuse which are reasonably foreseeable. These machines will not run on railway lines open to normal traffic. NOTE Other rail mounted railway maintenance and infrastructure inspection machines are dealt with in other European standards, see Technical Report CEN/TR 17498:2020. This document is also applicable to machines and associated equipment that in working mode are partly supported on the ballast or the formation. The requirements in this document are based on the assumption that the machines are used, operated and maintained by skilled person(s). This document does not apply to the following: requirements for quality of the work or performance of the machine; use of separate equipment temporarily mounted on machines; machines that utilize external power supplies such as the overhead contact line system for traction purposes or as a power source; hazards due to air pressure caused by the passing of high-speed trains at more than 200 km/h; operation subject to special rules, e.g. potentially explosive atmospheres; hazards due to natural causes, e.g. earthquake, lightning, flooding; working methods; operation in severe working conditions requiring special measures, e.g. corrosive environments, contaminating environments, strong magnetic fields; hazards occurring when used to handle suspended loads which may swing freely.