Mars lights

Red Mars Lights
From the 1968 Uniform Code of Operating Rules:


 * Rule 17 (b). Red Oscillating Headlight.-- On engines equippped with a red oscillating headlight, such headlight will be displayed by day or by night when train is stopped suddenly under circumstances in which adjacent tracks may be fouled, or when head end protection is required.


 * The red oscillating headlight must be extingquished when necessity no longer exists.


 * A headlight burning red is a signal for an approaching train on the same or adjacent track to stop before passing such headlight, and be governed by conditions.

Thomas 9011 wrote on Trains.com:


 * The light was used by a locomotive when the track next to it had people fouling the main line. It would typically be used during a unscheduled stop where passengers might get off. It would be used to warn the train coming in the other direction that there maybe people on the tracks. Some examples would be....


 * A passenger train broke down and the passengers are crossing the tracks to get to the road or bus on the other side.


 * A steam or diesel locomotive has broken down or derailed and there is people or machinery on the track next to it.


 * Special trains such as ski trains letting passengers off at a stop not normally serviced by the train.


 * The light moves back and forth just like a Mars light.


 * I believe the majority of railroads that carried passengers both in the steam and diesel era had red lights on their locomotives...Union pacific, Southern pacific, Milwaukee road, CB&Q, etc.


 * The red lights were probably abandoned around the late 1970's when Amtrak took over passenger service. Since the red lights were used mostly in passenger service there was really no need to keep them on the locomotives used by freight service.


 * Southern pacific was the last of the railroads to have those red lights installed on their locomotives mostly on their SD40T-2's in the early 1970's. That light along with the Mars light was gradually removed over the years. One of the rules of the FRA is that everything including the lights must be in operational condition. If a Mars light didn't work or the red light on the nose didn't work the locomotive could not be used. Compounding the problem was a shortage of parts and lens from a company that no longer existed.