(a) Warning signals, i.e., a white disk with the words “Occupied Camp Car” in black lettering during daylight hours and an illuminated white signal at night, displayed in accordance with § 218.75, § 218.77, or § 218.79 signify that employees are in, around, or in the vicinity of camp cars. Once the signals have been displayed—

1. (1) The camp cars may not be moved for coupling to other rolling equipment or moved to another location;
2. (2) Rolling equipment may not be placed on the same track so as to reduce or block the view of a warning signal; and
3. (3) Rolling equipment may not pass a warning signal.