Hierarchy of Control Explained

The Hierarchy of Control is a framework used across Australian workplaces to manage health and safety risks. Under the Work Health and Safety Act 2011 (WHS Act) and Safe Work Australia guidance, duty holders must eliminate risks so far as is reasonably practicable—and when that is not possible, minimise risks. The hierarchy ranks control measures from most to least effective, so you always consider the strongest option first.

For your White Card test and on-site practice, you need to know all six levels, why they are ordered this way, and how they apply to common construction hazards. This guide walks through each level with real examples you will encounter in the industry.

1. Elimination

Elimination means removing the hazard entirely so it no longer exists. It is the most effective control because there is no hazard left to cause harm. Safe Work Australia recommends always assessing whether elimination is reasonably practicable before moving down the hierarchy.

On construction sites, elimination might mean redesigning a process so a task is no longer needed. For example, if a roof requires maintenance, scheduling the work so it is done at ground level before the roof is installed eliminates the risk of falling from height. Another example: prefabricating components off-site in a controlled environment rather than welding at height eliminates both fall and exposure risks. Elimination is preferred whenever achievable, even if it requires changing how work is planned or sequenced.

2. Substitution

When elimination is not reasonably practicable, substitution involves replacing a hazardous substance, material, or process with something less harmful. The replacement should reduce risk while still allowing the work to be completed.

In construction, common substitution examples include using water-based paints instead of solvent-based paints to reduce inhalation of volatile organic compounds (VOCs), or switching to less toxic adhesives and cleaning products. Replacing timber formwork with steel or aluminium reduces splinter and puncture risks. Substitution is most effective when the alternative is genuinely less hazardous and does not introduce new risks.

3. Isolation

Isolation means physically separating the hazard from workers so they cannot be exposed to it. Barriers, enclosures, or exclusion zones keep people away from dangerous areas or equipment.

On site, trench barriers, fencing around excavations, and exclusion zones around crane swing radii are typical isolation controls. Confining noisy machinery to an enclosed area or storing hazardous chemicals in a separate, locked store isolates workers from those hazards. Isolation is especially important for mobile plant, excavations, and overhead work, where clear boundaries protect both workers and the public.

4. Engineering Controls

Engineering controls are physical changes to equipment, machinery, or the work environment that reduce risk. They do not rely on workers remembering to act safely; they build safety into the system. Engineering controls include guards, ventilation, and modifications to tools and plant.

Examples on construction sites include installing guardrails on scaffolding and platforms, local exhaust ventilation (LEV) for dust and fumes, machine guards on saws and grinders, and toe boards to prevent materials falling from edges. Using extendable tools to work at height instead of ladders reduces fall exposure. Because engineering controls are built into the work setup, they provide consistent protection across shifts and workers.

5. Administrative Controls

Administrative controls are procedures, policies, and practices that change how work is done. They rely on people following rules and instructions. Training, signage, Safe Work Method Statements (SWMS), job rotation, and safe work procedures are all administrative controls.

On a construction site, these might include conducting toolbox talks, displaying safety signs as per AS 1319, limiting time spent in noisy areas, and following SWMS for high-risk construction work. While essential for compliance and awareness, administrative controls are less reliable than higher-level controls because they depend on human behaviour and can be forgotten or ignored under pressure.

6. Personal Protective Equipment (PPE)

PPE is the last resort in the hierarchy. It protects the individual wearing it but does nothing to remove or reduce the hazard itself. PPE can fail, be worn incorrectly, or not be used, and it only protects the wearer—not others nearby.

Common construction PPE includes hard hats, safety glasses, hearing protection, high-visibility vests, gloves, steel-capped boots, and respiratory masks. PPE must be provided when risks cannot be adequately controlled by higher-level measures, and workers must be trained in its correct use, storage, and maintenance. It should always be used in combination with other controls, never as the sole measure for serious hazards.

Why the Order Matters

The WHS Act requires duty holders to eliminate risks so far as is reasonably practicable. If elimination is not possible, you must minimise risks by considering controls in order of the hierarchy. Elimination is most effective because it removes the hazard completely; PPE is the least effective because it only adds a layer between the worker and the hazard, which remains present.

In practice, you often use multiple controls together. For example, when working at height: eliminate where possible (e.g. ground-level assembly), use engineering controls (guardrails, scaffolding), apply administrative controls (SWMS, training), and require PPE (fall arrest harness, hard hat). Understanding the hierarchy helps you prioritise the strongest controls and recognise when relying only on PPE is insufficient for your White Card test and real-world safety.