Fire on the train tracks, apparently intentional. Why?

Mods, if this is in the wrong forum, please be so kind as to relocate accordingly.

Saturday night, hubby and I were driving to the movie theater (The Last Samurai. We both enjoyed it), and the road we were driving on ran parallel to the train tracks. Cumberland, for those who didn’t know, is a railroad town. Anyway. There, along the tracks, were small fires. The flames were probably about a foot high. They were right beside the ties. Approximately 15 of these little fires, spaced pretty evenly. There was a railroad employee by one group of them. The size and spacing suggests that they were intentionally set. But were they set by the railroad engineers, or by vandals? If the engineers set them, what is the purpose? If it’s any clue at all, it was bloody cold that night, and we had just had a snow storm here.

A factual answer would be great, but this question has been “burning” in me for days (sorry, sometimes I just can’t help myself), so even WAG’s would be welcome!

WAG - Thawing out switches. I remember pulling into Chicago on Amtrak in the middle of winter and workers there were using torches to unfreeze some switches.

Yep. Used to commute on the Burlington Northern, and in fact there are propane tanks along the tracks at several places with what appear to be lines running out to the tracks, I assume to keep switches from freezing. I have also seen crews using handheld torches on fozen switches closer in to the main station.

Well, I got a WAG from adirondack_mike, then a confirmation from Rhum Runner. Seems like we got ourselves a winner. Thanks, folks!