This European Standard is applicable by authorities involved in railway operation and may also be applied for light vehicles (e.g. trams, metros, etc. running on two rails) and their associated infrastructure, but not for systems such as rail-guided buses. It allows vehicles and infrastructures to be dimensioned and their compliance to be checked relative to the gauging rules. For the rolling stock and for the infrastructure, this standard is applicable to new designs, to modifications and to the checking of vehicles and infrastructures already in use. This document EN 15273-1 covers: - the general principles; - the various elements and phenomena affecting the determination of gauges; - the various calculation methods applicable to the elements shared by the infrastructure and by the rolling stock; - the sharing rules for elements taken into account in calculations specific to the infrastructure and to the vehicle; - a catalogue of European gauges.