Risk matrix
A risk matrix multiplies likelihood (how often the harm might occur) by consequence (how bad it would be if it did) to produce a risk rating — typically Low / Medium / High / Extreme. The 5×5 matrix is the dominant format in Australian WHS practice.
Legal context
A risk matrix gives a defensible, repeatable rating to every hazard so resource allocation can be prioritised. A typical 5×5 matrix has likelihood scaled from "Rare" to "Almost Certain" and consequence scaled from "Insignificant" to "Catastrophic"; the cell where they intersect gives the rating. Risk matrices are tools, not laws — but ISO 31000 (the parent risk-management standard ISO 45001 references) anticipates a matrix or equivalent semi-quantitative method. The "Extreme" cells typically trigger stop-work or immediate-escalation rules; "High" cells trigger formal SWMS / engineering controls; "Medium" cells trigger administrative controls; "Low" cells trigger monitoring only.
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.
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.
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.
Platform pillars
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47 WHS and HSWA terms with legal context, FAQs and regulator references.