What should be utilized when mobile equipment approaches the edge of an excavation and the operator cannot see the edge directly?

Utilizing a warning system with barricades is essential when mobile equipment approaches the edge of an excavation that is not directly visible to the operator. This approach enhances safety by providing a clear physical boundary that alerts the operator and others on site of the potential hazard. Barricades serve to prevent accidental entry into the excavation zone, which is crucial in avoiding falls or equipment tipping into the site.

The incorporation of a warning system adds an additional layer of safety, often utilizing signals or alarms that can be triggered when equipment nears the edge. This dual-faceted strategy ensures that operators are kept aware of their proximity to hazardous edges, fostering a safer work environment.

While other measures, such as using reinforced machinery or limiting the number of operators, may contribute to overall site safety, they do not address the specific visibility issue when operating near the excavation's edge. Continuous monitoring by external personnel, though valuable, may not provide the immediate feedback and physical barriers that a warning system and barricades would. Therefore, the selected option promotes direct prevention of incidents related to unseen edges effectively.