Users need to know where fall-arrest sits in the hierarchy of control for work at height (Figures 1.1 and 1.2) so they can tell whether the best protection that is practicable is actually in use. Equipment must be selected from an identification of the fall hazards of the work and an assessment of the fall risk, whether free, limited free or restrained. Legislation may place safe system of work duties on those responsible for people at height, and hazard identification and risk assessment against the hierarchy of control is a suitable way to meet them (AS/NZS 3931 gives risk analysis guidance).
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.