A unit train having a plurality of articulated cars for transporting one commodity or lading in one direction of travel between two geographical areas, and a different lading in the return opposite direction of travel. Alternate freight cars of one type, such as hopper cars, are transported in an unloaded condition in one direction of travel and are transported in a loaded condition in the return opposite direction of travel. Intervening freight cars such as flat cars, are transported in a loaded condition when the alternate cars are in unloaded condition, and are transported in an unloaded condition when the alternate cars are in loaded condition. The articulated cars have common trucks between adjacent ends of all the cars in the unit train to support the ends thereon. The trucks have a load capacity adequate to support one of the supported cars in fully loaded condition but inadequate to support both of the supported cars in loaded condition.