I have heard several rail recovery operations as well as contractors like Sperry and various rail grinders. They all use the regular road channels for communications with the railroad, to get track time and coordinate movements.
Sometimes they use one of the regular AAR channels for internal use. More often however they use the common itinerant, MURS or other business channels for person to person communications at the scene or on board the machinery. Most often I have heard them on 151.625, and other 151.xxx MHz. channels.
I did hear a work crew from a contractor once using FRS channels on a railgrinder, they had a hi-rail following along to put out grass fires and they were chatting back and forth.