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 transport costs 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.
The differences in revenue growth by mode are worth noting. The highest growth concerns oil pipelines, mainly related to the lack of investments in new capacity while the demand rose. Air and truck revenues per ton-mile increased in a similar fashion as both sectors are highly competitive, with energy a fundamental input factor. Rail and water transportation have experienced a lower growth in revenue in part because of their energy efficiency and propensity for economies of scale.