Track ballast is the material which forms the trackbed upon which railroad ties are laid. It is packed between, below, and around the ties. It is used to bear the compression load of the railroad ties, rails, and rolling stock; to facilitate drainage; and keep down vegetation that can compromise the integrity of the combined track structure. Ballast also physically holds the track in place as the trains roll over it. Not all types of railway tracks use ballast.
Good quality track ballast is made of crushed stone. The sharp edges help the particles interlock with each other.
Track ballast supports railway sleepers, which carry railway track.
Ballast must be irregularly shaped to work properly.
A railroad tie, crosstie, railway tie or railway sleeper is a rectangular support for the rails in railroad tracks. Usually laid perpendicular to the rails, ties transfer loads to the track ballast and subgrade, hold the rails upright and keep them spaced to the correct gauge.
Wooden ties are used on many traditional railways. In the background is a track with concrete ties.
Stone block from the Kilmarnock and Troon Railway
Steel ties
Wagons with new woodties in Sweden, 2016