Coal, grain, crude oil, ethanol, potash and frac sand commonly move in unit trains of 100 to 135 cars that stay together the whole trip and skip the classification yards entirely. Loaded coal trains often weigh 15,000 to 19,000 tons, so they run with distributed power and careful slack control. The cars cycle back empty to the same origin as one set, so the same train may pass through every few days.
That's a unit train of coal for the power plant, 135 loads, DPU on the rear, and she's heavy.
Many coal and grain unit trains load and unload on loop tracks at each end, so the train never has to uncouple or run around.
Also heard as
- unit
Related terms
Manifest
A freight train carrying a mix of car types and commodities for many different customers.
Drag
A slow, heavy, low-priority freight train, often of bulk loads or empties.
DPU
Distributed power unit: a locomotive placed mid-train or on the rear and controlled by radio from the lead unit.
Consist
The makeup of a train, listing its locomotives and cars in order with weights, loads and hazmat.