How do the railroads cope with the lack of heat from LED signal lamps to melt snow and ice? I've seen various freight railroads use the "Darth Vader" covers which apparently eliminate any kind of snow and ice build-up. However, what about the other railroads and transit agencies, e.g. NJ Transit, which use the "tri-light" arrangement? Won't these signals be prone to ice and snow build-up due to a lack of heat from the lamps that they relied upon before the advent of LED lamps?