General guidance for National Technical Specification Notices
This supports users of NTSNs and related processes such as authorisation for placing in service or placing interoperability constituents on the market. It covers both sets of NTSNs published by the Department for Transport (January 2021 and May 2025) and puts relevant industry-agreed guidance in a single place.
GEGN8601 is a large document that covers general topics relevant to multiple NTSNs. This includes the regulatory context, general implementation, and conformity assessment. It is intended to be used alongside the guidance notes for each NTSN (see resources).
This document is not meant to be read straight through. Instead, readers can look at any section that interests them separately from the others.
Frequently asked questions
NTSNs have a wide range of users, such as manufacturers, designers, transport operators, owners, and conformity assessment bodies. GEGN8601 Issue 1 contains guidance for all entities that need to understand and use NTSNs. It therefore covers lots of different topics from different perspectives and not all content will be relevant for everyone. These FAQs direct you to the relevant part of GEGN8601 Iss-1.
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General
What are NTSNs for? What do they contain? See G4.1.1.1, G2.1 (particularly G2.1.4 and G2.1.5) Do I need to apply NTSNs? See G1.2.3, G4.1.1 (particularly G4.1.1.3), G5.1.1, G5.1.2 Which NTSNs do I need to apply? See G2.3.2, G4.2, G4.3, G5.1.2 Is my product a subsystem or an interoperability constituent, or neither? See G2.3 Which version of an NTSN do I need to use? How do transitions between different versions of NTSNs work? • For vehicles, see G5.2 and Appendix B.
• For infrastructure, see G5.3.
• For functional subsystems such as operation and traffic management, see G5.4.
Where can I find the NTSNs? Visit the government’s website to find the NTSNs.
Where can I see what has changed since the previous NTSN? Note, RSSB publishes resources such as track-change versions of NTSNs to support application but the only official NTSNs are those published by the DfT.
Where do NTSNs apply? For example, do they apply in Northern Ireland? See G2.5, G1.2.7, G2.5.4. How do NTSNs relate to Technical Specifications for Interoperability (TSIs)? See G1.2, G4.6.1, Appendix A Can I use documents produced in the EU for TSIs (such as TSI application guides, ERA Opinions or Technical Advice) for application of NTSNs? See G4.6.3 How do NTSNs relate to safety and risk assessment? See G4.1.2, G4.1.3 Do I need to apply other standards that are referenced in NTSNs, such as ENs? See G2.2 What should I do if I think there is a problem with the NTSN requirements? See G7.1, G7.3 What do I do if I can’t meet applicable NTSN requirements? See G7.2.1, G7.3, G3.6 What are the responsibilities of transport operators in relation to NTSNs? See G3.4, G5.4 What are the ‘essential requirements’ of the Railways (Interoperability) Regulations (RIR)? See G1.2.2, Appendix C What is a ‘UK specific case’? What do I need to do if there is one? See G2.4.1, G2.4.2, G4.4 What is an ‘open point’? What do I need to do if there is one? See G2.4.1, G2.4.3, G4.4 What do I do if I cannot apply a National Technical Rule (NTR)? See G7.2.2 Where can I find guidance on specific NTSN requirements? See Appendix A -
For project entities for subsystems
I’m renewing or upgrading a vehicle or part of the rail network infrastructure – do I need an authorisation for placing in service (APIS)? See G5.1.1 How do I get an APIS for a subsystem in Great Britain? See G6.1.1.1, G6.1.2 What are my responsibilities in relation to NTSNs? See G3.2 Who is responsible for obtaining APIS for subsystems? See G3.2, G3.7 Who is responsible for meeting NTSN requirements? See G6.1.2, G6.1.4.4 Are technical files produced by the project entity or the conformity assessment body? See G6.6.2 What should be in a UK declaration of verification for a subsystem? See G6.8, Appendix E.2 What is an ISV and when can it be used? See G6.4 What should be in an ISV? See Appendix E.3 What should I do if I have questions regarding RIR or the APIS process? See G7.3 -
For organisations placing interoperability constituents on the market in the UK
How do I place an IC on the UK market? See G6.1.1, G6.1.3, G6.1.5 Can I use an EC declaration of conformity or suitability for use for placing an IC on the UK market? See G.2.3.3, G6.1.5, G6.7.4 What are my responsibilities in relation to NTSNs? See G3.3 Who is responsible for meeting NTSN requirements? See G6.1.3 What should be in a UK declaration of conformity or suitability for use for an IC? See G6.8, Appendix E.1 What should I do if I have questions regarding RIR or the process for placing an IC on the UK market? See G7.3 -
For conformity assessment or UK verification
What is an Approved Body (ApBo), Designated Body (DeBo), Notified Body (NoBo) or Assessment Body (AsBo)? Who do I need to appoint? See G3.5, G6.1.4 When do I need to appoint an ApBo and/or DeBo? For subsystems, see G6.1.2.5 What does an ApBo or DeBo need to assess? See G.6.1.1.3, G6.5.1 (note, this is based on NB-Rail’s RFU-ST-711) What are the assessment modules? Where can I find them? See G6.2.1 Which assessment modules can I use? For subsystems, see G6.2.1, G6.2.2
For ICs, see G6.2.1, G6.2.3
Who decides which assessment modules to use? See G6.3.1 Which modules should I choose for assessment of my product? See G6.3.1.
For subsystems, see also G6.3.2 (note, this is based on NB-Rail’s RFU-STR-092)
Do I always need an ApBo/DeBo assessment, or can it be done in-house? See G6.1.3, G.6.2.3.10 How do modules SH1 and CH1 (UK verification or conformity based on full QMS plus design examination) work? See G6.5.3 (note, this is based on NB-Rail’s RFU-STR-059) Can the applicants of module CB (UK-type examination) and module CD (conformity to type based on QMS of the production process) be different? How does this work? See G6.5.4 (note, this is based on NB-Rail’s RFU-STR-700) How long are my certificates or ISVs valid for? See G6.7.1, G6.7.2, (note, these are based on NB-Rail’s RFU-STR-060)
For ICs, see also G6.7.3 (note, this is based on NB-Rail’s RFU-STR-060), G6.7.4
What should be in a conformity assessment body technical file or conformity assessment report? See G6.6.1, G6.6.2, G6.6.3, Appendix D (note, these are based on NB-Rail’s RFU-STR-011)
Resources
NTSN Guidance Notes
GEGN8601 Issue 1 only covers topics that apply to more than one NTSN. For guidance specific to each NTSN, RSSB produces separate guidance notes. These are published in the standards catalogue for:
- Accessibility (ACC) NTSN
- Control Command and Signalling (CCS) NTSN
- Energy (ENE) NTSN
- Infrastructure (INF) NTSN
- Operation and Traffic Management (OPE) NTSN
- Rolling stock – Locomotives and Passenger (LOC&PAS) NTSN
- Rolling stock – Freight Wagons (WAG) NTSN and Rolling stock – Noise (NOI) NTSN
- Safety in Railway Tunnels (SRT) NTSN.
Other guidance
The Department for Transport (DfT) and Office of Rail and Road (ORR) publish guidance that covers NTSNs, and related legislation and processes.
Department for Transport guidance
Office of Rail and Road guidance
Templates
GEGN8601 Issue 1 Appendix E contains templates for UK declarations and Intermediate Statements of Verification (ISVs).
Note: there is no requirement to use these templates for UK declarations or ISVs. They are provided as guidance only to help applicants and support use of consistent formats. They have the same structure as equivalent European Commission templates and meet the UK regulatory requirements for information.