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.