Why Are There Rocks on the Train Tracks?

TURIN – Anyone who has ever taken a train will have noticed a curious and seemingly inexplicable feature: the tracks are immersed in a bed of stones. But why? What are all those stones doing under and around the rails? That bed of stones has a specific name: it is called ballast. It is not just a superficial covering, but a deep layer that can vary from 15 to 50 centimeters. The stones are not there by chance: they perform fundamental functions …