Who are the caution, clear, and danger signals displayed for?

Caution, clear, and danger signals are primarily displayed for motormen, who are the operators of trains. These signals serve as critical communications that guide the motormen in safely operating the train within the railway system. Each type of signal conveys specific information about the track ahead, such as whether it is safe to proceed (clear signal), whether they should be prepared to stop or slow down (caution signal), or if there is a hazard requiring immediate action (danger signal).

Understanding these signals is crucial for motormen as they need to make quick decisions based on the information provided. The clarity and immediacy of these signals are fundamental to ensuring the safe and efficient operation of trains, thus making them specifically relevant to the motormen's duties. Other options, such as passengers, track workers, or supervisors, do not interact directly with these operational signals in the same way, which is why they are not the primary audience for such communications.