Did you know the function of stones on railway track?

Track ballast(stones) forms the trackbed upon which
railway sleepers (UK) or railroad ties (US) are laid. It is packed between, below, and around the ties.
It is used to facilitate drainage of water, to distribute the load
from the railroad ties, and
also to keep down vegetation that might interfere with the track structure.
This also serves to hold the track in place as
the trains roll by. It is
typically made of crushed stone, although ballast has sometimes consisted of
other, less suitable materials.
The term "ballast" comes from a nautical term for the
stones used to stabilize a ship.