Stones, generously scattered on the railway tracks, of course, are not chance there. They even have a special name - Ballast.
Railway canvas, despite the seeming monolithicness and strength, in fact a very capricious object, daily exposed to extreme loads from passing multi-torque compositions. Such pressure can quickly lead to the deformation of the paths, so the load coming from rails to the sleepers should be evenly distributed over the surface. It is for this that a ballast is intended, which transfers the load on the surface area of the earth canvas, filling the entire space between the elements of the railway tracks.
In addition, the ballast serves to drain from the railway tracks of water, freely passing it into the gap between the stones.
Ballast is the most important element of the railway canvase. Over time, Ballast stones crumble and wear out, so they are replaced with new ones.