What are National Notified Technical Rules (NNTR)?

NNTRs are specific national standards that apply to railway projects in areas where European TSIs are not applicable, contain 'open points', or where specific local legacy systems (like national signaling) must be maintained.

Can a NoBo also act as a DeBo?

Yes, a single organization can hold accreditations to act as both a Notified Body (NoBo) and a Designated Body (DeBo). This allows them to offer a 'one-stop-shop' assessment for both EU and national rules.

Is a DeBo assessment always required?

A DeBo assessment is required whenever there are applicable National Rules (NNTR) for the project. If a project is fully covered by TSIs with no open points or specific national constraints, a DeBo might not be needed, but this is rare in complex infrastructure projects.

Navigating National Rules: The Role of the Designated Body (DeBo)

National compatibility is crucial for cross-border rail. Discover how a Designated Body (DeBo) validates compliance with National Notified Technical Rules (NNTR).

December 11, 2025 8:29 am

What is a Designated Body (DeBo)?

A Designated Body (DeBo) is an independent conformity assessment body responsible for verifying that a railway subsystem complies with the National Notified Technical Rules (NNTR) of a specific country.

While European regulations (TSIs) aim to harmonize the railway network, unique local infrastructure, legacy signaling systems, and specific environmental conditions still exist in each Member State. The DeBo closes this gap by ensuring that a new train or signaling system is technically compatible with the specific national network where it intends to operate.

Why Do We Need a DeBo?

European TSIs do not cover every aspect of the railway system (“Open Points”). A DeBo is required to assess these specific local requirements, such as:

Legacy Signaling: Compatibility with older national systems (e.g., PZB in Germany, KVB in France, ATB in Netherlands).
Infrastructure Constraints: Specific gauge limits, pantograph widths, or voltage variations not fully covered by TSI.
Climate Conditions: Specific national requirements for extreme weather protection.

Comparison: DeBo vs. NoBo

The distinction between a NoBo and a DeBo is the most common point of confusion in railway certification. The difference lies entirely in the set of rules they verify.

Feature	Notified Body (NoBo)	Designated Body (DeBo)
Scope	European Union Harmonization	National Compatibility
Reference Standards	TSI (Technical Specifications for Interoperability)	NNTR (National Notified Technical Rules)
Validity	Valid across all EU Member States	Valid only in the specific country (e.g., Germany only)
Outcome	EC Certificate of Verification	Certificate of Verification (National)

The DeBo Assessment Process

The DeBo assessment runs parallel to the NoBo process and is essential for obtaining the final authorization from the National Safety Authority (NSA) or ERA.

1. Identification of National Rules

The applicant must identify which NNTRs apply to their project. These rules are “notified” by the Member State to the European Commission.

2. Verification

The DeBo audits the design, production, and testing phases to ensure the subsystem meets these local rules. This often involves checking interfaces with existing national infrastructure.

3. Certification

Once compliance is proven, the DeBo issues a certificate. This certificate, combined with the NoBo certificate (for TSI compliance) and the AsBo report (for safety), forms the complete Technical File needed for authorization.