What does 'ballast' refer to in railway construction?

The term 'ballast' in railway construction specifically refers to the gravel used to stabilize the tracks. Ballast serves an essential role in maintaining the structural integrity of the railroad bed. It provides a stable base for the ties and rails, helping to distribute the weight of the trains and reduce the risk of track deformation. Additionally, ballast assists with drainage, preventing water accumulation that could undermine the tracks.

In contrast, wooden supports for the tracks are known as ties or sleepers, which provide a foundation for the rails but do not stabilize the tracks in the same way as ballast. Metal tracks are the actual rails that the train runs on but do not contribute to the stability directly like ballast does. Cement mixture is often used in segments of rail construction but is not referred to as ballast and does not serve the same purpose of track stabilization.