Aunit train, also called ablock train or atrainload service, is atrain in which allcars (wagons) carry the same commodity and are shipped from the same origin to the same destination, without being split up or stored en route.[1] They are distinct fromwagonload trains, composed of differing numbers of cars for various customers.[2]
Unit trains enable railways to compete more effectively with road and internal waterway transport systems. Time and money are saved by avoiding the complexities and delays that would otherwise involve assembling and disassembling trains atrail yards near the origin and destination.
Unit trains are particularly efficient and economical for high-volumecommodities. Since they often carry only one commodity, cars are of all the same type; often identical. Some commodities (e.g., coal) can be loaded at the origin while the train moves slowly on a loop track. The procedure is reversed at the receiving end, and because there generally is not any commodity to be hauled in the opposite direction, the train returns empty. In theUnited States theSanta Fe is credited with operating the first true unit train, hauling coal from a mine nearRaton, New Mexico to a steel mill atFontana, California.[3]
Unit trains are typically used for the transportation of bulk goods. These can be solid substances such as:
Bulk liquids are transported in unit trains made up oftank cars, such as:
Food, such as:
Other examples include:
...trainload service (point to point, complete train for one customer) or wagonload service (single wagons for various customers, assembled into trains)