What type of safety measure must be in place on unprotected edges?

The requirement for guardrails on unprotected edges is a critical safety measure designed to protect workers from falls, particularly in construction and renovation settings. Guardrails provide a physical barrier that can prevent individuals from accidentally stepping or falling off the edge of a rooftop, scaffold, or other elevated work areas. This safety measure is mandated by regulations to ensure that workers have adequate protection against the hazards of working at heights.

Guardrails are specifically designed to meet safety standards, which typically stipulate their height, strength, and installation requirements, making them a reliable form of fall protection. Their correct installation and maintenance can significantly reduce the risk of serious accidents, which is why they are considered essential where there is a risk of falling.

While other options like warning lights, signage, and netting might contribute to safety in different ways, they do not provide the same level of direct physical protection as guardrails do. For example, signage can communicate hazards but does not prevent falls, while netting might catch falling objects rather than preventing a person from falling. Thus, guardrails stand out as the most effective and necessary safety measure for unprotected edges.