This European Standard specifies the technical requirements to minimize the specific railway hazards of trailers and associated equipment, which can arise during the commissioning, the operation and the maintenance of trailers when carried out in accordance with the specification given by the manufacturer or his authorized representative. This European Standard applies to trailers that are not intended to interact with operate signalling and control systems. Other machines are dealt with in other European Standards; see Annex E. These trailers are not designed or intended for operating signalling and control systems and are only intended to work and run under special operating conditions specifically designated by the infrastructure manager. These trailers are not intended to be vehicles as defined in the Interoperability Directive and are not permitted to run on the railway lines open to normal traffic. If this is required, they will need to be authorised or placed into service as set out in the Interoperability Directive 2008/57/EC. Part 1 of this European Standard deals with the technical railway requirements; Part 2 deals with requirements for the trailer to be declared conformant by the manufacturer, except in the case of trailers classified in Annex 4 of the Machinery Directive 2006/42/EC which require conformity check in conjunction with a notified body. Additional requirements can apply for running on infrastructures with narrow gauge or broad gauge lines, lines of tramways, railways utilising other than adhesion between the rail and rail wheels, and underground infrastructures. This European Standard is also applicable to trailers and associated equipment that in working configuration are partly supported on the ballast or the formation. Where two or more trailers are used together to transport loads in a fixed formation, e.g. where a metal container is fixed to two small trailers, the whole system is treated as a trailer for the purposes of compliance with the requirements of this European Standard.