why do they put a lot of rocks on the railway is there a scientific reason??

Answer 1

Like others have said, to maintain a level state without constant on location grading and to prevent sinking. Also, to cut down on ground vibration. If it were a solid bed, vibrations would carry through into surrounding ground more effectively. With it all being "loose" gravel, the rocks can vibrate to disperse energy. Yes, there is some vibration, but it would be a lot worse.

Answer 2

Railroad beds, like road beds, are designed to drain water away from the tracks, so there is usually a bed of rock and gravel resulting in fast drainage away from the tracks. At the same time, this drainage often accumulates in areas fairly near the tracks where drainage is poor, forming small artificial wetlands. These unnatural conditions combine to form different zones, some in which water is scarce, others in which water is abundant.

Answer 3

The rocks provide extra ordinary support to the rails itself from sinking.

Answer 4

they do it to keep the surface level, but prevent the rails from sinking into it (as they would if they used sand or mud instead of rocks).

Answer 5

its called ballast. it holds the ties nicely in place and drains away the rain so the ties dont rot