Why are there always these stones under the train?

Ask the mouse…

The mouse has found out: Each track system consists of several layers. On what is under the tracks – earth or rock, a protective layer of gravel, sand and stones comes first. The top layer is very important: the gravel – small stones so.

These stones are, so to speak, the bed for the rails, one also speaks of a “belt”. They must have broken edges so that they can interlock, be pushed into each other. These stones are constantly in motion to cushion vibrations and vibrations that cause the trains that drive over it.

In addition, rails are not only moving through the trains that drive over it. But also through different temperatures: rails are made of steel – this expands somewhat in heat, in cold it is drawn together. In order to have enough space for expansion in heat, small gaps have been left between the rails in the past, the so-called “rail thrust”. This monotonous “da-dam-da-dam” noise came about during train trips. But the wheels of the trains were greatly worn by the rail thrust.

Today, the rails are avoided by welding successive rails together. In addition, they are anchored to the web thresholds so that they can no longer extend in length. The voltages and the pressure which then arise during heating are partially released downwards, otherwise the material simply has to withstand it.

The stones otherwise ensure that rain can drain well. This is especially important in the cold months so that the rails are not damaged by freezing water.

See: https://www1.wdr.de/radio/wdr2/themes/frag-doch-mal-die-maus/schotter- Balken-100.html