Template deepdive — Linear Safety Chain (LSC-001)
The Linear Safety Chain is the simplest template in WCGW Safety Suite: a five-node chain from system boundary to technical implementation. It works with all ASIL levels (A–D) and covers phases from Item Definition through Technical Safety.
Item → Hazard → Safety Goal → Functional Safety Requirement → Technical Safety Requirement
1. Anatomy of the chain
| Node | Key prefix | Phase | ASIL |
|---|---|---|---|
| Item | ITM-xxx |
Item Definition | — (defines scope) |
| Hazard | HAZ-xxx |
HARA | — (determined by SE+C+R) |
| Safety Goal | SG-xxx |
HARA | A–D assigned here |
| FSR | FSR-xxx |
Functional Safety | Inherited from SG |
| TSR | TSR-xxx |
Technical Safety | Inherited from FSR |
Each node connects via: MITIGATES (SG → Hazard), DERIVES_FROM (SG → Item), REFINES (FSR → SG, TSR → FSR).
2. Using the LSC template
The LSC template is a starting point — not a manual build. Here's how the real workflow works:
1. Select LSC-001 — pick the template from the WCGW template picker. The tool pre-configures five concept types (Item, Hazard, Safety Goal, FSR, TSR) and three relation patterns (MITIGATES, DERIVES_FROM, REFINES).
2. Import concepts — the template generates placeholder entries for all five nodes, linked in the correct order: Item → Hazard → Safety Goal → FSR → TSR.
3. Revise each concept — edit the auto-generated concepts to match your system (e.g. replace the placeholder Item with "Autonomous Mobile Robot R2, ≤1.5 m/s, shared warehouse"). Fill in the Hazard with both the hazardous event and operational situation. Assign ASIL on the Safety Goal.
4. Add relations — the template pre-creates the relation links, but you may need to adjust them or add context (e.g. customising MITIGATES with a rationale).
5. Review the chain — verify the completed chain: ITM-001 → HAZ-001 → SG-001 → FSR-001 → TSR-001. One complete, auditable chain built from a template, not from scratch.
3. Two worked examples
AMR collision (ASIL D)
| Node | Content |
|---|---|
| Item | AMR R2, ≤1.5 m/s, 200 kg, shared warehouse |
| Hazard | Collision with human during autonomous navigation |
| Safety Goal | Avoid collision with humans. ASIL D |
| FSR | Maintain ≥ 0.5 m distance from persons. ASIL D |
| TSR | SICK S300 laser scanner, ≥ 5 m range, 100 ms stop. ASIL D |
Press brake light curtain (PL d / SIL 3)
| Node | Content |
|---|---|
| Item | Hydraulic Press Brake PB-3000, 3000 kN, manual load cell |
| Hazard | Finger/hand crush during closing stroke while positioning workpiece |
| Safety Goal | Prevent access to pinch point during stroke. PL d / SIL 3 |
| FSR | Interrupt and reverse stroke if hands detected in danger zone. PL d |
| TSR | Type 4 light curtain (IEC 61496), 14 mm resolution, redundant output to SIL 3 safety PLC. PL d |
The LSC is standard-agnostic — the same chain works for ISO 26262, IEC 61508, and ISO 13849.
4. ASIL propagation
ASIL flows top-down: SG (assigned) → FSR (inherited) → TSR (inherited). No node can be lower than its parent. For decomposition (e.g. splitting ASIL D into two ASIL B(D) paths), step into the ASIL Decomposition Template (AD-001) — it composes cleanly with LSC.
5. Common pitfalls
- Missing operational situations in hazards → ASIL can't be evaluated
- Mixing FSR/TSR → auditors flag implementation details in functional requirements
- No ASIL on Safety Goal → entire chain has blank ASIL
- Chain too long — five nodes only; branch into HMW or MCT when complexity grows
- LSCs in isolation — they are the skeleton, not the final deliverable. Merge, decompose, allocate, and validate.
6. Getting started
Select LSC-001 from the WCGW template picker. The tool pre-configures the five required concept types and three relation patterns, then generates placeholder concepts for you to revise.
Build one chain per hazard. Then compose.
Need help moving from LSCs to a full safety case? Contact us.