Question

why are iron rails of railway track fixed over wide wooden or concrete sleepers

Answer 1

Trains are heavy objects that run on tracks. Many trains run on the tracks and apply a great pressure on a less surface area. So there is a chance that the tracks may go down into the ground. In order to prevent sinking of tracks , wooden or concrete sleepers are laid below the tracks so that great pressure exerted by the trains falls over a large surface area.