The rails and perpendicular beams are usually then placed on a foundation made of concrete or compressed earth and gravel in a bed of ballast to prevent the track from buckling (bending out of its original configuration) as the ground settles over time beneath and under the weight of the vehicles passing above.
Railtransport is an energy-efficient and capital-intensive means of mechanised land transport.
Rail lines that carry little traffic are often built as single track, to be used by trains in both directions; "passing sidings", which consist of short stretches of double track, are provided along the line to allow trains to pass one another, and to travel in opposite directions.
Railtransport is the most energy efficient means of mechanised land transport.
Railtransport is also one of the safest modes of transport, and also makes highly efficient use of space: a double-tracked rail line can carry more passengers or freight in a given amount of time than a four-laned road.
Rail lines that carry little traffic are often built with a single track used by trains in both directions; on rail lines like these, "crossovers", "passing loops" or "passing sidings", which consist of short stretches of double track, are provided along the line to allow trains to pass each other, and travel in opposite directions.