Hierarchy of control
The hierarchy of control is the rank-ordered preference for risk treatment: eliminate the hazard, then substitute, then isolate, then engineer, then administer, then PPE as a last resort. Higher controls reduce risk more reliably than lower controls because they do not depend on people behaving correctly under stress.
Legal context
The hierarchy of control is the foundation framework of WHS risk treatment, codified in s17 of the model WHS Act and elaborated in WHS Regulation 36 (six levels): Level 1 — Eliminate the hazard (most effective; the duty-holder must consider this first). Level 2 — Substitute the hazard with something safer. Level 3 — Isolate the hazard from people. Level 4 — Use engineering controls (guards, interlocks, ventilation). Level 5 — Use administrative controls (procedures, training, signage, work scheduling). Level 6 — Use personal protective equipment (PPE). PPE is the lowest-ranked control because it relies entirely on people wearing it correctly every time and offers no defence in depth. A risk assessment that jumps straight to PPE without showing reasoning against levels 1–5 is not a defensible record.
Practical use
In every SWMS, JSA, risk assessment and incident corrective action, the hierarchy must be applied explicitly: name the level of each control, not just the control itself. RAE IQ's drafting engine enforces this — every generated control is tagged with its hierarchy level.
Regulator references
The binding-law and regulator-guidance sources behind this term.
Common questions
Why is PPE the lowest control?
PPE only protects an individual person, only while they are wearing it correctly, and only if it is the right PPE for the hazard. It does not change the hazard itself. Higher controls (elimination, substitution, isolation, engineering) reduce the hazard at source — a much more reliable defence.
Do I have to consider every level?
Yes — and you must consider them in order. WHS Reg 36 requires duty-holders to work through the hierarchy from elimination downwards. Skipping a level without recorded reasoning is a common audit finding.
Where this shows up in RAE IQ
Related terms
Risk assessment
A risk assessment is the structured analysis of a hazard: what is the hazard, who could be harmed and how, what is the likelihood and consequence, what controls reduce the risk, and what residual risk remains. The output drives the hierarchy-of-control decisions and the SWMS / SOP / register entries that flow from it.
ALARP
ALARP — As Low As Reasonably Practicable — is the principle that risk must be reduced as far as is reasonably practicable, applying hierarchy-of-control reasoning, and only stopping when further control would be grossly disproportionate to the residual risk. It is the operational expression of the s18 reasonably-practicable test.
SWMS
A Safe Work Method Statement is a written document required by WHS Regulation 299 for any high-risk construction work. It identifies the work, the hazards, the controls (in hierarchy-of-control order), the residual risks, and the person responsible. The principal contractor must keep it for the life of the project.
Reasonably practicable
Reasonably practicable is the qualifier on almost every WHS duty: it means doing what can reasonably be done in the circumstances, having regard to the likelihood of harm, the degree of harm, what is known about the hazard, the availability and suitability of controls, and the cost of controls. Cost is always the last factor.
Platform pillars
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47 WHS and HSWA terms with legal context, FAQs and regulator references.