What is "road train"

Truck \Truck\, n. [L. trochus an iron hoop, Gr. ? a wheel, fr. ? to run. See Trochee, and cf. Truckle, v. i.]

1. A small wheel, as of a vehicle; specifically (Ord.), a small strong wheel, as of wood or iron, for a gun carriage.

2. A low, wheeled vehicle or barrow for carrying goods, stone, and other heavy articles.

   Goods were conveyed about the town almost exclusively in trucks drawn by dogs.
   --Macaulay.

3. (Railroad Mach.) A swiveling carriage, consisting of a frame with one or more pairs of wheels and the necessary boxes, springs, etc., to carry and guide one end of a locomotive or a car; -- sometimes called bogie in England. Trucks usually have four or six wheels.

4. (Naut.)

   1. A small wooden cap at the summit of a flagstaff or a masthead, having holes in it for reeving halyards through.

   2. A small piece of wood, usually cylindrical or disk-shaped, used for various purposes.

5. A freight car. [Eng.]

6. A frame on low wheels or rollers; -- used for various purposes, as for a movable support for heavy bodies.

7. a motorized vehicle larger than an automobile with a compartment in front for the driver, behind which is a separate compartment for freight; esp.

   1. such a vehicle with an inflexible body.

   2. A vehicle with a short body and a support for attaching a trailer; -- also called a tractor[4].

   3. the combination of tractor and trailer, also called a tractor-trailer (a form of articulated vehicle); it is a common form of truck, and is used primarily for hauling freight on a highway.

   4. a tractor with more than one trailer attached in a series. In Australia, often referred to as a road train.

n. (context US Australia Canada English) A transport concept consisting of a conventional prime mover truck pulling two or more trailers.

A road train or land train is a trucking vehicle of a type used in remote areas of Argentina, Australia, Mexico, the United States, and Canada to move freight efficiently. The term road train is most often used in Australia. In the United States, the terms triples, turnpike doubles, and Rocky Mountain doubles are commonly used for longer combination vehicles (LCVs). A road train has a relatively normal tractor unit, but instead of towing one trailer or semi-trailer, it pulls two or more of them.