Glossary · Risk assessment and risk reduction
Hierarchy of controls
In occupational and machine safety, the hierarchy of controls is the ordered preference for elimination, substitution, engineering controls, administrative controls and personal protective equipment. Measures higher in the order are generally more effective because they depend less on human behavior.
- Machine safety
- Risk assessment
- USA
In one sentence
The hierarchy of controls ranks measures from elimination down to PPE, so behavior-dependent controls are used only where better ones are impracticable.
Example
To reduce the risk of hand injuries at a manual press, a plant first replaces it with an automated press (substitution), then adds a light curtain, then trains staff, and only then issues cut-resistant gloves.
How it applies
- Order: Elimination, substitution, engineering controls, administrative controls, PPE. ISO 45001 sets this order for employers, and it is widely used in US occupational safety guidance.
- Machine safety: The manufacturer-side counterpart is the three-step method of ISO 12100. Both express the same principle: design first, protective measures second, reliance on people last.
- Technical documentation: Document why a higher-ranked control was not practicable when a lower one is chosen. Auditors and courts look for this reasoning.
- Evidence: Controls are often combined. Record which layer addresses which hazard so that removing one layer does not go unnoticed.
Hierarchy of controls vs. three-step method
The hierarchy of controls is framed for employers controlling workplace risks. The three-step method is framed for machine designers. On an integrated line, both apply: the manufacturer reduces risk by design, and the user applies the hierarchy to the residual risk.