When workmen are on, under, or between an engine or rolling equipment, where must a blue signal be attached?

A blue signal must be attached to the controlling engine and be visible to the engineer to ensure the safety of workmen who are on, under, or between an engine or rolling equipment. The purpose of the blue signal is to convey to the engineer that work is being performed, which prohibits any movement of the equipment until the work is completed and the signal is removed. This procedure is a critical safety measure, as it helps prevent accidental injuries that could occur from the movement of trains while workmen are in a potentially hazardous area.

The positioning of the blue signal on the controlling engine, where it is visible to the engineer, ensures that the engineer is fully aware of the work crew's presence and understands the need to halt operations. Proper placement of the blue signal is vital in maintaining a safe work environment and reinforcing strict adherence to safety protocols.