Glossary · Evidence, assurance and traceability
Evidence chain
In safety assurance, an evidence chain is the linked sequence from a requirement or hazard through the design decision, implementation, verification, and user information. A break anywhere in the chain leaves the claim unsupported.
- Systems engineering
- Technical documentation
In one sentence
An evidence chain links a hazard or requirement to design, implementation, verification and user information without gaps.
Example
The evidence chain for a crushing hazard on a press runs from the risk assessment entry to the decision for a light curtain, its installation record, the stopping time test and the warning in the operating manual.
How it applies
- Evidence: Build the chain with explicit trace links, not by naming conventions. Check it for gaps before release and after changes.
- Machine safety: Start from the hazard. Every hazard that needs risk reduction should end in verified measures and, where residual risk remains, user information.
- Technical documentation: The last link is often the manual. Structured safety messages, such as a DITA hazard statement with an ID, make that link precise.
- Audit: Auditors typically pick a hazard and follow the chain. A chain that can be followed in minutes shows control.
Evidence chain vs. traceability
Traceability is the general ability to follow links. An evidence chain is one specific path through those links that supports a claim.