Source: P.O. Roberts (1999) "Logistics and Freight Transportation: Review of Concepts Affecting Bulk Transportation", World Bank.

Shipment Size and Transport Costs

The principle of economies of scale in transportation particularly applies to freight distribution as costs tend to be inversely proportional to shipment size. Freight shipped in 10 pounds parcels would cost about $1,000 per ton while freight shipped on a 2 million pounds barge load would cost $2 per ton. This favors a specialization of shipments according to the value of what is being transported.