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Technical Specifications for Interoperability

​​​​​​​​​​​​​​​​​​​​​​​​Technical Specifications for Interoperability (TSI) define the technical and operational standards which must be met in order to satisfy the ‘essential requirements’ and to ensure the ‘interoperability’ of the European railway system. TSIs also set out expected performance levels.

The essential requirements can be summarised as safety, reliability and availability, health, environmental protection, technical compatibility and accessibility.

The formal definition of interoperability in the Interoperability Directive 2008/57/EC External link is "the ability of the rail system to allow the safe and uninterrupted movement of trains which accomplish the required levels of performance".

TSIs are intended to foster the development of a single European railway system and therefore they apply to all mainline railways within the European Union.

You can find TSIs on the EUR-Lex website External link. RSSB maintains an up-to-date list of TSIs.

The Department for Transport (DfT) is the body responsible for liaison with the European Commission about TSIs. Information about TSIs can be found on the DfT's Rail interoperability and standards page External link.

Developing and amending TSIs

For further information please see the page on the Developing and amending TSIs.

​How do TSIs relate to National Technical Rules?​

National Technical Rules (NTRs) are used for the following purposes:

  • To fill identified 'open points' in TSIs
  • To support UK specific cases in TSIs
  • To support a derogation from a TSI
  • To set out requirements to maintain technical compatibility between existing assets (or processes) that do not conform to the requirements of TSIs and new, upgraded or ​renewed assets conforming to TSIs.

The Railway Interoperability Directive 2008/57/EC External link requires each Member State to notify to the European Commission the NTRs in use. Some Railway Group Standards are notified as NTRs for the purposes listed above.

Who must comply with TSIs?

The Railways (Interoperability) Regulations 2011 External link mandate compliance with TSIs on organisations involved in the GB mainline railway system. These regulations transposed the Railway Interoperability Directive 2008/57/EC External link into domestic legislation and came into force on 16 January 2012.

The Railways (Interoperability) Regulations 2011 have been amended by the Railways (Interoperability) (Amendment) Regulations 2013 External link, which came into force on 01 January 2014. For further information, see the Legislative Framework page​.

Following the scope extension the TSIs apply to the GB mainline railway system. The scope of mainline railway system where the TSIs apply can be found on the DfT website External link.

You must comply with a TSI if you are building new railway sub-systems or carrying out a major upgrade or renewal of an existing railway sub-system. Replacement of parts of a sub-system on a like-for-like basis, for example replacing track with track of a similar specification, does not trigger a legal obligation to comply with TSIs. The TSIs also contain requirements for interoperability constituents (ICs).

For further information on ICs and the national procedure to address the issue of ICs and specific cases, see the page on interoperability constituents.

Advice about whether a specific project must comply with TSIs can be obtained from the DfT.​

The TSIs

The TSIs cover the whole mainline railway system and for new projects, national rules only apply in the following circumstances:

  • Technical compatibility (to ensure technical compatibility with the legacy rail system where it is not designed and built to TSIs)
  • Specific cases (where GB need to do something different)
  • Open points (where a national rule provides a solution for the open point)

TSIs related to national technical rules are:

Refer to this table for information relating to these TSIs including any amendments to the TSIs, other associated documents such as TSI Application Guides.  The table also provides hyperlinks to TSIs for telematics applications.

All TSIs will eventually be published as Regulations and not Decisions as previously. Therefore, they do not require transposition into UK law and are directly applicable.

Errors in TSIs

The DfT Rail interoperability TSI FAQ External link page describes how errors in TSIs are dealt with.

RSSB maintains a​TSI application issues log for recording information relating to problems that have been encountered when applying TSIs in GB. This is used to support discussions when TSIs are being amended.

The log is managed by RSSB but issues may be contributed by any railway organisation working with a TSI, including those on the GB mainline railway and HS1. Where appropriate, a document setting out further information relating to a particular issue should be included in the log via a hyperlink.

Any issue with a TSI should be raised with the appropriate industry sector representative on the standards committee for the relevant railway sub-system.​

The Guide to the TSI application issues log provides further information on how the log is to be managed and populated, including the role that the RSSB-facilitated Standards Committees may fulfil in providing a forum for industry discussion about suspected errors in TSIs and how to address them.

Please contact ​Vaibhav Puri on 020 3142 5446 if you require further information r​egarding TSIs.​

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