On the 14th April 2008 the European Commission published its official decision concerning a technical specification for interoperability relating to the ‘energy’ sub-system of the trans-European high-speed rail system (notified under document number C(2008) 807). The Decision shall apply from 1st October 2008.

The Commission's Decision established the first technical specification for interoperability (TSI) concerning the trans-European high speed energy sub-system whand will be will be applicable to all new, upgraded or renewed infrastructure of the trans-European high speed rail system.

Application of this TSI to high-speed lines already in service

In respect of infrastructure installations already in operation, this TSI applies to sections of line being upgraded or renewed. In this particular context, it relates fundamentally to the application of a migration strategy which enables an economically justifiable adaptation of existing Energy installations to be made. Whilst the TSI can be fully applied to new installations, implementation on existing lines may require modifications of existing equipment. The degree of modification necessary will depend on the extent of conformity of the existing equipment. The following principles apply in the case of the High Speed Energy TSI. When the Member State requires a new putting into service, the Contracting Entity shall define the practical measures and different phases which are necessary to achieve the required levels of performance. These phases may include transition periods for placing into service with reduced levels of performance.

Particular features on the British network

The railway infrastructure within Great Britain was historically built to a smaller gauge than the other railways of Europe. It is uneconomic or impracticable to increase the gauge, and therefore the target gauge for Great Britain will be the UK1 issue 2 (see High Speed Infrastructure TSI).

Variable contact wire height and gradient will be retained on electrified lines in Categories II and III. The nominal wire height adopted in future on upgraded lines in the Great Britain will not be less than 4,700 mm. However where constraints require it, the minimum permissible wire height is 4,140 mm, sufficient to allow the passage of electric trains built to UK1B gauge.

Within six months from when the decision comes into force, Member States are required to notify the following types of agreement to the Commission within of the attached TSI:

• National, bilateral or multilateral agreements between Member States and Railway Undertaking(s) or Infrastructure Manager(s), agreed on either a permanent or a temporary basis and required due to the very specific or local nature of the intended train service.
• Bilateral or multilateral agreements between Railway Undertaking(s), Infrastructure Manager(s) or Member State(s) which deliver significant levels of local or regional interoperability.
• International agreements between one or more Member State(s) and at least one third country, or between Railway Undertaking(s) or Infrastructure Manager(s) of Member States and at least one Railway Undertaking or Infrastructure Manager of a third country, which deliver significant levels of local or regional interoperability.

The official text was published in the Official Journal of the European Union on 14th April 2008.