- To hold the sleepers in place, both laterally and longitudinally (as they in turn hold the rails in place & help maintain gauge.
- To distribute the load of entire moving cargo from rails into the sub-base/formation (ground below the ballast.
- To maintain support of and distance between the cross ties.
- To restrain heat expansion & contraction (due to thermal stresses), and ground movements.
- As ballast provide cushioning effect (thus rendering elastic property to the railway track).
- The air voids present between the stones absorb vibrations and make it comfortable, not only for the traveling passengers but also for the residents next to tracks.
- To facilitate drainage & stop building up of precipitation from rough weather (which can help — relieve frost heaves & maintain necessary shear stress in sub-base).
- To overcome weed & plant growth from underneath.
- To absorb much of the sounds & noises produced by train movements.
- Minor adjustments can be made in the track as and when required.