What is one condition that allows for a reduction in the number of watchpersons at a construction site?

The option regarding the building layout allowing a continuous line of sight is correct because this condition enhances safety at the construction site. When there is a continuous line of sight throughout the site, it enables a single watchperson to effectively monitor the area, ensuring they can observe all activities and respond promptly to any emergencies or unsafe conditions. This visual accessibility means that fewer personnel may be needed without compromising safety.

The other conditions presented do not facilitate a reduction in the number of watchpersons. A site lacking a fire safety plan would actually necessitate more watchpersons to ensure safety measures are adhered to. If no construction is occurring, while it might seem to imply fewer watchpersons are needed, it does not guarantee that all potential hazards are controlled, so this wouldn't justify a reduction. Similarly, limiting construction hours can affect the number of workers on site but doesn't inherently allow for fewer watchpersons without considering the safety requirements during those hours.