What is the purpose of ballast in railways?

The purpose of ballast in railways is primarily to provide stability and drainage. Ballast consists of crushed stone or gravel that is placed underneath and around the railroad ties (sleepers), forming a solid foundation for the track. This stability is crucial as it helps maintain the alignment of the tracks, ensuring that they remain level and properly positioned under the weight of passing trains. Properly laid ballast also facilitates adequate drainage, preventing water accumulation that could lead to erosion or destabilization of the track structure.

While reducing noise pollution may be a secondary benefit of certain types of ballast materials, it is not the primary role of ballast. Similarly, ballast does not inherently increase the speed of a train, as the speed is more directly influenced by factors such as track design, train type, and operational practices. Regarding supporting electrical systems, ballast does not serve this function either, as electrical system support typically relies on other components designed specifically for that purpose.