If you have been to a railway station or have travelled by train at some point in your life, you must have noticed that there are stones laid on the railway tracks, surrounding the metal bars which are laid to assist the movement of the train.
Stones are placed and laid on railway tracks for one simple scientific reason. The vibrations produced when the train moves on the metal tracks are very high and create a lot of noise and movement. The stones on the tracks, which are called ballasts, are placed to absorb the noise and the vibrations.
While track ballasts are laid on every train platform across the globe, you must have noticed that stones are not laid down on metro tracks. One other difference is also that metro tracks are made up of concrete, as opposed to metal and stone.
Train ballasts cannot be made from just any type of stone. You cannot use stones found in water bodies or with rounded edges, as they will roll over when the train passes. One can only lay stones with sharp and coarse edges to be the train ballasts.
Why are track ballast stones not laid on metro tracks?
As opposed to railway tracks, the tracks on the metro station are very busy. While trains pass through the station every few hours, metro trains cross platforms every 5 to 10 minutes. This means that laying stones on the tracks and maintaining the same can be very difficult.
The metro tracks are rarely made on ground level. They are either made above the ground or below the ground. This means that it is difficult to maintain them and laying stones constantly can lead to higher maintenance costs for the same.
To reduce the vibrations, metro tracks are fitted with concrete rather than stone. Though the cost of concrete is higher than stone, there is next to no wear and tear, and minimal maintenance, as opposed to with train ballasts.
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