This TSI concerns the control command and signalling, infrastructure, energy, operation and traffic management, and rolling stock (locomotives and passenger units) subsystems. It applies to new, renewed and upgraded tunnels which are located on the rail network of the European Union.
By definition, a railway tunnel is an excavation or a construction around the track provided to allow the railway to pass for example higher land, buildings or water. The length of a tunnel is defined as the length of the fully enclosed section, measured at rail level. A tunnel in the context of this TSI is 0.1 km or longer. Where certain requirements apply only to longer tunnels, thresholds are mentioned in the relevant clauses of the TSI.