What should be placed to mark an unsafe condition in the mine?

A danger board is specifically designed to mark unsafe conditions within a mine setting. It typically conveys clear and immediate warnings to the miners and personnel about hazards that need to be addressed or avoided. This is crucial in a mining environment where safety is of utmost importance due to the various risks involved.

While warning tape and traffic cones can be used for general safety and to mark hazards, they are not as formal or universally recognized as a danger board. Signboards generally serve a broader purpose, including information or instructions, not solely indicating unsafe conditions. The use of a danger board ensures that everyone on site understands the severity of the situation and acts accordingly, which is vital for maintaining safety standards in a potentially hazardous environment like a coal mine.