From the IEC 61508 base standard to demonstrating compliance under EN 50126, EN 50128/EN 50657 and EN 50129
Why functional safety?
Electrical, electronic and programmable electronic systems now perform tasks whose failure can put people, the environment and physical assets at risk. Functional safety is the part of overall safety that depends on precisely this: a safety function must be executed correctly when called upon, and no fault may go undetected.
The scope covers both random hardware failures and systematic faults. Functional safety is not a property of individual components but a property of the system across its entire lifecycle.
The standards landscape — one framework, many sectors
IEC 61508 provides the cross-sector framework as the basic safety publication. It describes the complete safety lifecycle and assigns safety functions to safety integrity levels SIL 1 to SIL 4.
Sector-specific standards have been derived from it, adapting the same approach to the conditions of each industry:
In the rail sector, EN 50126 takes the role of the umbrella standard. It addresses not only safety but, with equal weight, reliability, availability and maintainability — together known as RAMS. Part 1 defines the generic RAMS process along the system lifecycle, from the concept phase through to decommissioning; Part 2 sets out the systems approach to safety. Building on this are EN 50129, with its requirements for the safety case, and EN 50128 and EN 50657 for software.
From requirement to defensible evidence
The effort involved depends on how the system is classified. In rail, this classification is derived from tolerable hazard rates (THR) and translated into safety integrity levels. Getting there follows a clear chain: system definition including operating modes, hazard identification, risk analysis and evaluation, derivation of safety requirements, implementation in the design, verification and validation — and finally the documented evidence.
Then there is the regulatory framework. The Common Safety Method for Risk Evaluation and Assessment (CSM-RA) and the Technical Specifications for Interoperability (TSI) also govern how evidence is compiled and how it is assessed by independent bodies. Compliance with the standards is therefore not an end in itself, but the precondition for authorisation, entry into service and acceptance by the operator.
We support you through every phase — from the first hazard analysis to the accepted safety case.
Are you looking for a person to support you in the individual steps of the functional safety evidence chain?
An adaptation of the QM according to the selected measures for safety-related systems is pending. We take over task packages from the evidence chain and process them for you. This can start with a GAP analysis to see where the deficits lie or with the implementation of a process through hazard identification to the creation of evidence.
If you would like to learn more, please feel free to contact us.
Do you want to develop one or more employees into Functional Safety Managers and need support?
A precise job description and assignment to the responsible persons is a basic requirement for conscious and effective action to maintain and achieve functional safety. Responsibility can only be exercised through the identification with the necessary tasks and requirements. Authority and an understanding of safety processes and requirements are important basic building blocks.
A system needs a person responsible for the life phases and a coordinator for the execution of the safety-related activities in the phases. If partial development takes place, the persons responsible must be named here as well in order to clearly delineate the phases and work products. At the end of the project, one person or a small group of persons must be able to show how the requirements and objectives of IEC 61508 have been achieved.
We accompany your employee from the beginning and support him actively in the implementation of the individual process steps of the respective standard.
We are always at your disposal for further questions.
