Glossary · Evidence, assurance and traceability
Bidirectional traceability
Also known as: Two-way traceability
German: Bidirektionale Rückverfolgbarkeit
In systems engineering, bidirectional traceability means that trace links can be followed in both directions: forward from a requirement to its design elements, implementation and tests, and backward from any design element or test to the requirement that justifies it.
- Systems engineering
- Verification
In one sentence
Bidirectional traceability lets you follow links forward from requirements to design and tests and backward from tests or code to their requirements.
Example
A reviewer starts at a failed test case of a safety function and traces back to the software requirement and the hazard it mitigates, then forward again to every other test affected.
How it applies
- Engineering: Forward traces show that every requirement is implemented and verified; backward traces reveal design elements or code without a requirement ("gold plating" or undocumented functions).
- Change: Impact analysis depends on both directions: from a changed requirement to affected tests, and from a changed component to affected requirements.
- Functional safety: Standards such as IEC 61508 expect traceability between safety requirements, design and verification; bidirectional links make that evidence reviewable.
- Documentation: Keep safety-relevant statements in manuals traceable to their requirement or risk-assessment entry, so a change to one flags the other.
Bidirectional vs. one-way traceability
One-way traceability (requirement to test only) proves coverage but cannot show whether a test or code module has any justification. Bidirectional traceability adds that backward view without requiring a second set of links: each Trace link is simply queryable from both ends.