Final answer:
Rail transport is the biggest competitor to inland water transport, given its efficiency in moving large volumes of goods and the flexibility of rail networks.
Step-by-step explanation:
Based on similar cost and service characteristics, the biggest competitor for inland water transport is rail transport. Given their ability to move large volumes of goods efficiently over land, railroads serve as a practical alternative, especially for routes where natural waterways may not be accessible. Furthermore, the invention of the intermodal container in the 1950s revolutionized the shipping industry by enabling goods to be easily transferred between ships, trains, and trucks, which further enhanced the competitive edge of rail transport.
Rail networks are not limited by natural waterways and can extend the reach of transportation to areas that are not served by rivers or canals. Moreover, rail transport can leverage economies of scale when it comes to the shipment of bulk goods, similar to that of inland water transport. Both modes can offer substantial cost savings especially if the destination or point of origin is near a rail line or waterway. However, when considering energy efficiency, container ships have an advantage as they consume lesser energy per ton-kilometer relative to trains.