The hierarchy of control, used properly

The order is the point

The hierarchy of control ranks control measures from most effective to least. You are required to work down it: eliminate the risk if you reasonably can, and only move to a lower level when elimination is not reasonably practicable.

This is not a menu to pick from. A SWMS where every hazard is controlled by "wear PPE and take care" is the clearest possible signal that no one thought about the job, and it is what inspectors look for first.

The six levels

Working from most effective to least:

• Elimination — remove the hazard entirely. Prefabricate at ground level so nobody goes on the roof. Do not work in wind above 40 km/h.
• Substitution — replace it with something less hazardous. Use a battery tool instead of a petrol one in an enclosed space. Use a panel hoist instead of hand-passing modules up a ladder.
• Isolation — separate people from the hazard. Lock out and tag the switchboard. Fence a 3-metre exclusion zone under the work area.
• Engineering controls — change the physical setup. Perimeter guard rail. Trench shoring. Local exhaust ventilation. Tool lanyards.
• Administrative controls — change how people work. Permits, exclusion distances, spotters, rotation in heat, pre-start briefings, sequencing so edge protection comes down last.
• Personal protective equipment — the last line, because it protects one person and only if it is worn, fitted and maintained correctly.

How to tell a real control from a filler one

A real control names a thing that will be done, by whom, and when. "Perimeter guard rail installed to both working edges before any worker steps onto the roof" is a control. "Ensure safe work at heights" is a wish.

A useful test: could a worker who has never been to this site read the control and know exactly what to do? If not, it is not written yet.

The other test is the residual risk. If your initial rating is extreme and your residual rating is also extreme, the controls have not done anything and the work should not proceed as planned. If your initial is extreme and residual is low, be sure the controls really justify that — a harness alone does not take a fall risk to low.

Combining levels

Most serious hazards need more than one level. A fall risk is typically controlled with an engineering control (guard rail) plus an administrative one (no work within 2 metres of an unprotected edge) plus PPE (harness inspected before use). The engineering control does the work; the others catch what it misses.

When you list them, lead with the highest level that applies. A reader should be able to see at a glance that you did not jump straight to PPE.

Common questions

Is PPE ever enough on its own?

Rarely, and never for a high-consequence hazard. PPE is the lowest level of the hierarchy because it does nothing to the hazard itself — it only reduces harm if it is worn correctly at the moment things go wrong. Use it to back up higher controls, not to replace them.

What is the difference between isolation and engineering controls?

Isolation separates people from the hazard — a locked-out switchboard, a fenced exclusion zone. Engineering controls change the physical setup so the hazard is less likely to cause harm — guard rails, shoring, ventilation. In practice they often work together.

Do I have to use every level of the hierarchy?

No. You have to work down from the top and use the highest level that is reasonably practicable, then add lower levels as needed. What you cannot do is skip to the bottom because it is cheaper or easier.

Keep reading

• What is a SWMS?What the document actually is, when the law requires one, and what has to be in it.
• The 18 categories of high risk construction workThe full list, what each one means on a real job, and where Victoria differs.
• SWMS vs JSA vs safe work procedureFive documents, constantly confused. Which one the law actually requires.