The Hierarchy of Controls Explained

The hierarchy of controls that applies to most OHS hazards sets out the order of control measures, running from elimination to substitution, followed by engineering, administration, and finally, personal protective equipment.

In the field of working at heights however, the law lays out the equipment and systems to match.

The hierarchy demystified

The five-level hierarchy includes:

Level 1: Undertake the work on the ground or on a solid construction

Level 2: Undertake the work using a passive fall protection device

Level 3: Undertake the work using a work positioning system

Level 4: Undertake the work using a fall injury prevention system

Level 5: Undertake the work from ladders, or implement administrative controls

“Wherever practicable”

You can only move to a lower level where it is “not practicable” to use a higher order control.

The National Code of Practice – Prevention of Falls in General Construction explains that “’practicable” lists four factors to take into account, including the:

  • severity of the hazard or risk
  • state of knowledge
  • ways to remove or mitigate the hazard or risk
  • cost of removing or mitigating the hazard or risk

Level 1: Undertake the work on the ground or on a solid construction

This first level aims to eliminate the hazard. The Code of Practice suggests a host of measures, from using extendable handles on paint rollers to tilt-slab concrete wall construction, as alternatives to working at height.

A “solid construction” must have:

  • structural strength to support people and materials. Examples include a platform or scaffold
  • a non-slip surface free from trip hazards and at a readily negotiable gradient
  • edge and void protection (provided by a guardrail, for example) and;
  • safe access and egress, that could be provided by a ladder or stairway

Level 2: Undertake the work using a passive fall protection device

“Passive fall protection device” includes height safety products that once installed, don’t need to be altered. Examples: fixed or mobile scaffolds, guardrails, scissor lifts, cherry pickers and roof safety mesh.

Level 3: Undertake the work using a work positioning system

If eliminating the risk is not practicable and neither are the level 2 controls, consider the category of safeguards referred to as “work positioning systems”

These typically include industrial rope access systems and travel restraint systems. They prevent workers falling over an unprotected edge and are normally harnesses attached by lanyards to roof anchors or static lines, or harnesses with ropes and friction devices.

Because their effectiveness depends entirely on the skills of their users and how well the equipment is maintained, both users and their supervisors should undertake competency-based training before implementing level 3 safeguards.

Level 4: Undertake the work using a fall injury prevention system

Often confused with work positioning systems, fall injury prevention systems are fundamentally different. While work positioning systems prevent the fall from occurring at all, level 4 controls merely minimise the distance of the fall.

Examples include safety nets, catch platforms and individual fall arrest systems (IFAS). All must be installed by people with specialist technical skills and workers using IFAS must also be highly trained.

The Code of Practice notes that “An IFAS requires considerable skill to use safely, and in the event of an arrested fall, it is likely to cause some physical injury to the user”.

Workers using IFAS should never work alone and an emergency plan needs to be put in place to allow a speedy rescue.

Level 5: Undertake the work from ladders, or implement administrative controls

The last resort for working safely at height encompasses ladders and procedures, or “administrative controls”.

The reason these two are grouped together at the end of the risk control sequence is that they are equally poor ways to control the risk of a fall.

The Code details the correct use of ladders and outlines the need for stringent documentation of administrative controls.

The bottom line

Aside from meeting your obligations, it is good business to install the higher level controls like guardrails and walkways wherever possible rather than relying on fall prevention and fall arrest systems.

Simple, low maintenance systems like guardrails are less costly over their lifetimes, require little training to use and allow a broader spectrum of workers to do the job safely.