Why there are no stones on metro tracks like railways?

Metro rail is fastest growing means of mass rapid transit in India. Being cheaper is another reason of Metro’s popularity. First metro in the country started operations way back in 1984 in Kolkata. Kolkata network is only metro rail network that is controlled by the Indian Railways. The second oldest after Kolkata Metro is Delhi Metro. Currently, Metro has reached an operational network of over 660 km across 12 cities. Apart from 12 cities, there are 15 other cities in India have over 500 km of metro lines under different stages of implementation.

You must have travelled in metro. Did you ever noticed Why Metro Tracks are Ballast(stone) less. You must have always seen small ballasts lying on railway tracks. But you must have ever seen the ballast lying on the metro tracks. But you will never see ballast lying on the metro tracks. Do you know why this happens? If not, then let’s know the reason behind it.

Why are there stones on railway tracks?
To know reason as to why there are no stones on metro tracks, you must first understand why there are broken stones on railway tracks. Actually, they are called ballasts. Trains are heavy in nature specially Goods trains. When the train passes through the track, there is lot of noise and loud vibrations due to heavy weight of train. The space between ballasts lying on the track reduce this noise and absorbs spread of the sleepers under the track at the time of vibration. But the maintenance of these ballasts lying on the track costs a lot. Also, sometimes railway tracks have to be blocked in their maintenance.

Why are there no ballasts in the metro?
Metro tracks are built without ballasts because metro tracks cannot be blocked for repeated maintenance. The track is either above ground or below ground. It is not possible to maintain the ballast track in such a place, because the frequency of metro train is between 2 to 4 minutes. Therefore, blocking their tracks can become a problem for the common people. For metro, only concrete tracks without ballast have to be made, these tracks are expensive to make, but their maintenance has to be done negligibly. Metros are relatively low in weight. Still there exists need to absorb vibrations. Ballast less tracks have different designs to absorb vibrations.

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