Source: BTS, Table 3-21. Note: Cents per ton-mile.
In a competitive market, the revenue a transport company generates depends on its costs and profit margin. High revenue per ton-mile is directly related to high operating costs associated with this revenue generation. The most important factor related to the transport cost is the amount of energy spent on each unit being moved, which is commonly related to the economies of scale that can be achieved with each transport mode. Under such circumstances, maritime transportation is the mode with the lowest cost per ton-mile. Although air transportation has higher transport costs than road transportation, the difference is not excessive. Air cargo is usually carried over much longer distances than road and concerns high-value goods.