Final answer:
The assertion that trench boxes do not prevent cave-ins but protect workers is true. These protective systems are designed to provide safety in the event of a trench collapse and are mandatory under OSHA regulations.
Step-by-step explanation:
The statement that trench boxes don't prevent cave-ins but do protect people is True. Trench boxes, also known as trench shields, are structures made of steel or aluminum designed to protect workers from injuries in the event of a trench collapse. While they do not reinforce the trench to prevent a cave-in, they are able to withstand the forces of the soil that caves in, thereby providing a safe space for workers within the trench. It's important for workers to understand the use of trench boxes as part of safety measures on construction sites. They are a form of protective system required by the Occupational Safety and Health Administration (OSHA) when trenching and excavation work is being performed.