Railway sleepers often sit on a bed of small stones that act as ballast. This ballast material stretches well beyond the width of the sleepers and to quite a depth. But why does it have to be stones? Could anything else be used either physically or economically? 1. Ballast provides a firm surface for the railway track and spreads the load on the subsoil. To do this it also needs to drain well. Ballast that is of sufficient depth will distribute the load. And to restrict lateral movement of the rails, ballast extends outwards in shoulders on either side of the track.
展开▼
