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D
Deadweight tonnage (dwt) - The weight in long tons (2,240 pounds) that a vessel can carry, including freight, bunkers (fuel), and ship’s stores.
Demurrage - Charges assessed for keeping a piece of carrier equipment too long.
Density - The weight per cubic unit of measure.
Density rate - A rate based upon the density and shipment weight.
Deregulation - Revisions or complete elimination of economic regulations controlling transportation. The Motor Carrier Act of 1980 and the Staggers Act of 1980 revised the economic controls over motor carriers and railroads, while the Airline Deregulation Act of 1978 will eventually eliminate economic controls over air carriers.
Detention charges - The charge assessed by the motor carrier when the shipper/receiver holds a truck trailer beyond the free time allowed for loading and unloading.
Dispatching - The carrier activities involved with controlling equipment; involves arranging for fuel, drivers, crews, and equipment, and terminal space.
DNA - Delta Nu Alpha, a professional transportation group.
Double bottoms - A motor carrier operation involving two trailers being pulled by one tractor.
Double stack - Two container, one on top of the other loaded on a railroad flatcar; an intermodal service.
Drayage - Local trucking; used today to describe the truck movement of containers and trailers to and from railyards to port areas.
Driving time regulations - Rules administered by the U.S. Department of Transportation that limit the maximum time a driver may drive in commerce; both daily and weekly maximums are prescribed.
Drop shipments - Shipments delivered to a handful of designated sites.
Dual operation - A motor carrier that has both common and contract carrier operating authority.
Dunnage - The packing and bracing of materials
