WHY IS THE HEADLIGHT ON SOME 3RD PARTY LOCOS FLASHING LEFT AND RIGHT?
Mars lights were popular as warning devices on later steam locomotives and diesels. There were several varieties, but they all operated on the principle of projecting an oscillating beam of light to warn of an oncoming train. Because of their complex moving parts, they required a lot of maintenance, and Mars lights fell out of use by US railroads in the 1970s. Today, they have been replaced by alternating “ditch” lights, which do not require moving parts and are therefore less expensive to maintain. The effect you describe in MSTS is how these lights operated. The “swirling” and moving beam of light was projected far in front of the locomotive and moved from side to side of the tracks. Hope this helps.
