Hierarchy of controls: examples from real sites

Why there is an order

A sign saying “wear your glasses” relies on every person remembering every time. A guard that stops the sparks reaching their face doesn’t rely on anyone. That gap is the whole idea behind the hierarchy: fixes at the top work without the worker’s help.

SafeWork NSW refers to the hierarchy of controls on its psychosocial hazards page. The row below quotes the line.

Eliminate

Remove the hazard completely. If nobody goes up, nobody can fall. Pre-assemble roof trusses at ground level and lift them as one piece. Order materials cut to length so nobody runs a saw on site. This is the strongest control and the hardest to find, so ask the question early.

Substitute

Swap the hazard for something safer. Use a water-based cleaner instead of a solvent. Choose a battery tool in a confined space in place of a petrol one. The hazard shrinks, though it doesn’t vanish.

Isolate

Keep people away from the hazard. Fence off the excavator’s swing radius. Put the noisy compressor in a shed. Mark an exclusion zone under a lift and keep a person at the gate. The hazard is still there, but nobody is in reach.

Engineering controls

Change the equipment or the setup so the hazard is controlled by design. Edge protection and guardrails on a slab. Wet cutting or on-tool extraction on a saw, to cut dust at the source. Interlocked guards on machinery. These work every day, shift after shift.

Administrative controls

Change how people work. Safe work method statements, permits, signs, inductions, job rotation, toolbox talks. They’re cheap and quick. They’re also easy to skip when the job is behind. Use them to support the stronger controls, not to replace them.

PPE

Gloves, glasses, hearing protection, respirators, harnesses. PPE is the last layer. It protects one person at a time, and just when it fits, is worn and is in good order. Many sites reach for it before anything else because it’s easy to buy. Treat that as a signal to look up the list.

Combining controls

Real jobs use more than one level. A saw gets wet cutting (engineering), a marked exclusion zone (isolation), a sign (administrative) and a respirator for the operator (PPE). Each layer covers a failure in the one above. What matters is that the layers at the top are doing most of the work.

Using a report to pick the level

When a worker reports a hazard, ask how far up the list the fix can go. A missing edge barrier is a guardrail job (engineering), not a sign. A dusty cut may be a wet-cutting job today and a change of material later. Write the control you chose, and why, on the report.

• Fall from height: remove the work at height, then guardrails, then harnesses
• Silica dust: change the material or cut method, then extraction, then respirators
• Noise: quieter plant, then enclosure, then rotation, then hearing protection
• Manual handling: mechanical aid or delivery to the point of use, then team lifts