This International Standard applies to electric traction overhead contact line systems in heavy railways, light railways, trolley busses and industrial railways of public and private operators. It applies to new installations of overhead contact line systems and for the complete reconstruction of existing overhead contact line systems. This standard contains the requirements and tests for the design of overhead contact lines, requirements for structures and their structural calculations and verifications as well as the requirements and tests for the design of assemblies and individual parts. This standard does not provide requirements for conductor rail systems where the conductor rails are located adjacent to the running rails.