What should be displayed when the prescribed markers become inoperative?

When the prescribed markers become inoperative, displaying a red flag by day and a red light by night is necessary to ensure safety and alert other railway personnel of the situation. The use of a red flag during daylight hours serves as a clear visual warning to other train operators and staff that the markers are not functioning and that extra caution is required. Similarly, a red light at night maintains visibility under low-light conditions while conveying the same alert regarding the inoperative markers. This consistent use of red signals across both day and night emphasizes safety and helps prevent accidents, ensuring that other trains are aware of potential hazards on the line.

Other options do not convey the appropriate level of caution required for inoperative markers. A yellow flag and green light may imply a different status or level of caution, which would not be suitable in this case. A red light to the rear does not communicate the inoperative status effectively to the entire train crew or other train operators. Lastly, a white flare is typically used for visibility and signaling but does not specifically indicate that prescribed markers are inoperative. Thus, the use of red signals—both flags and lights—is critical for maintaining safety and awareness in railway operations.