SG Burning Switch

I recently ran across a crossing with a switch starting at the very edge of the road. To my surprise there was a fire under the switch. Under closer inspection, there were about 4-5 3 gallon tanks on each side that had fire comming out of them. They were placed in between the ties right under the rails probably containing kerosene or desil.
My mother saw the same thing about 5 minutes later and called the 1800 number. They told her they were to warm up the rails because of the weight of the desils on the rails.
Maybe someone could elaborate on this, and maybe explain why this is not needed on NG operations. Or is it?