Piggyback transportation refers to the transportation of goods where one transportation unit is carried on the back of something else. It is a specialised form of intermodal transportation and combined transport.

Etymology

''Piggyback'' is a corruption of ''pickaback'', which is likely to be a folk

etymology Etymology () The New Oxford Dictionary of English (1998) – p. 633 "Etymology /ˌɛtɪˈmɒlədʒi/ the study of the class in words and the way their meanings have changed throughout time". is the study of the history of the form of words ...

alteration of ''pick pack'' (1560s), which perhaps is from ''pick'', a dialectal variant of the verb ''pitch''.

Examples

Rail

In rail transport, the practice of carrying trailers or semi-trailers in a train atop a

flatcar A flatcar (US) (also flat car, or flatbed) is a piece of rolling stock that consists of an open, flat deck mounted on a pair of trucks (US) or bogies (UK), one at each end containing four or six wheels. Occasionally, flat cars designed to carry ...

is referred to as "piggybacking". Early drawings of the Liverpool & Manchester Railway c1830 show road coaches being piggybacked on railway flat wagons. The rail service provided for trucks which are carried on trains for part of their journey is referred to as a rolling road, or

rolling highway In rail transportation, a rolling highway or rolling road is a form of combined transport involving the conveying of road trucks by rail, referred to as Ro-La trains. The concept is a form of piggyback transportation. The technical challen ...

. A related transportation method is the rail transport of semi-trailers, without road tractors, sometimes referred to as "trailer on flatcar (TOFC)". In the United States, TOFC traffic grew from 1% of freight in 1957 to 5% in 1964 and 15% in 1986. A railway wagon of one

track gauge In rail transport, track gauge (in American English, alternatively track gage) is the distance between the two rails of a railway track. All vehicles on a rail network must have wheelsets that are compatible with the track gauge. Since many ...

can be carried on a flat wagon ( transporter wagon or rollbock) of another gauge. In addition, an entire train of coupled wagons of one gauge can be carried on continuous rails on a train of flat wagons of another gauge. This was achieved by the

Commonwealth Railways The Commonwealth Railways were established in 1917 by the Government of Australia with the Commonwealth Railways Act to administer the Trans-Australia and Port Augusta to Darwin railways. It was absorbed into Australian National in 1975. O ...

on the Marree railway line in South Australia between Telford Cut and

Port Augusta Port Augusta is a small city in South Australia. Formerly a seaport, it is now a road traffic and railway junction city mainly located on the east coast of the Spencer Gulf immediately south of the gulf's head and about north of the state c ...

in the mid-1950s. Japan Railways planned a similar " Train on Train" scheme, but at much higher speeds, to operate from 2016.

Marine

Small ships of all kinds can be piggybacked on larger ships. Examples include lifeboats,

landing craft Landing craft are small and medium seagoing watercraft, such as boats and barges, used to convey a landing force (infantry and vehicles) from the sea to the shore during an amphibious assault. The term excludes landing ships, which are larger. ...

, and minesweepers on motherships, as well as

midget submarine A midget submarine (also called a mini submarine) is any submarine under 150 tons, typically operated by a crew of one or two but sometimes up to six or nine, with little or no on-board living accommodation. They normally work with mother ships, ...

s on larger

submarine A submarine (or sub) is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability. The term is also sometimes used historically or colloquially to refer to remotely op ...

s, such as those used for the 1942 Japanese submarine attack on Sydney.

Air transport

The 1930s British Short Mayo Composite, in which a smaller, four-engine

floatplane A floatplane is a type of seaplane with one or more slender floats mounted under the fuselage to provide buoyancy. By contrast, a flying boat uses its fuselage for buoyancy. Either type of seaplane may also have landing gear suitable for land, m ...

aircraft named Mercury was carried aloft on the back of a larger four-engine

flying boat A flying boat is a type of fixed-winged seaplane with a hull, allowing it to land on water. It differs from a floatplane in that a flying boat's fuselage is purpose-designed for floatation and contains a hull, while floatplanes rely on fuselag ...

named Maia, enabled the Mercury to achieve a greater range than would have been possible had it taken off under its own power. The American

Space Shuttle The Space Shuttle is a retired, partially reusable low Earth orbital spacecraft system operated from 1981 to 2011 by the U.S. National Aeronautics and Space Administration (NASA) as part of the Space Shuttle program. Its official program n ...

was carried on top of specially-modified

Boeing 747 The Boeing 747 is a large, long-range wide-body airliner designed and manufactured by Boeing Commercial Airplanes in the United States between 1968 and 2022. After introducing the 707 in October 1958, Pan Am wanted a jet times its size, ...

Shuttle Carrier Aircraft when the shuttle landed at places other than Kennedy Space Center.

Space

In space transportation systems, a smaller

satellite A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioiso ...

that is carried as a secondary payload on a launch is said to be "piggybacked" on the main launch. It is often the case of

small satellite A small satellite, miniaturized satellite, or smallsat is a satellite of low mass and size, usually under . While all such satellites can be referred to as "small", different classifications are used to categorize them based on mass. Satellites ca ...

s and

cubesats A CubeSat is a class of miniaturized satellite based around a form factor consisting of cubes. CubeSats have a mass of no more than per unit, and often use commercial off-the-shelf (COTS) components for their electronics and structure. CubeSat ...

, since they can not usually afford accessing space on a dedicated launch and they choose instead to take profit of the remaining payload capacity in a big satellite launch. However, this is usually at the cost of not being able to fly to their desired

orbit In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as ...

and having to remain on a similar orbit to that of the big satellite.

Military

The metal caterpillar treads of a

tank A tank is an armoured fighting vehicle intended as a primary offensive weapon in front-line ground combat. Tank designs are a balance of heavy firepower, strong armour, and good battlefield mobility provided by tracks and a powerful ...

wear out quickly when travelling long distances on ordinary roads. Also, tracked vehicles seriously damage the tarmac layer of ordinary roads (unless the caterpillar treads are specially fitted with rubber pads to avoid this). It is therefore necessary to provide tank transporters, which have rubber tires, to the battlefield.

Human locomotion

A person carrying someone else on their back is most commonly seen in the modern day in the form of a parent carrying a child. It may also feature in the context of play or sport, and evidence of this dates back to

ancient Greece Ancient Greece ( el, Ἑλλάς, Hellás) was a northeastern Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity ( AD 600), that comprised a loose collection of cu ...

where games involving piggyback riding were combined with the requirement of catching or throwing a ball.Gardiner, E. Norman, 'Athletics of the Ancient World', Oxford: OUP, 1967, illustration 209 / facing p. 230

Gallery

File:001015 gauge buster.jpg, Transporter wagon File:MBC Ua 235A.JPG, Timber wagon on rollbocks File:Crocodile Waggon transports locomotive bodily.gif, "Crocodile Waggon" of GNR 1907 File:South Australian Railways narrow gauge locomotive T232 on broad gauge crocodile car.jpg, A

South Australian Railways South Australian Railways (SAR) was the statutory corporation through which the Government of South Australia built and operated railways in South Australia from 1854 until March 1978, when its non-urban railways were incorporated into Aust ...

T class narrow-gauge locomotive on a broad-gauge crocodile car File:Atlantis on Shuttle Carrier Aircraft.jpg, The Space Shuttle ''Atlantis'' atop a

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeedin ...

File:Trajekt im Strom.jpg, Bonn–Oberkassel train ferry File:ROLA Kelenfold.JPG, Rolling road File:Maia and Mercury, August 1938 (Our Generation, 1938).jpg, Short Mayo Composite just before the first trans-Atlantic flight, August 1938 File:Handball pick-a-back Ancient Greece.jpg, Youths playing a ball game, circa 500 B.C. File:Tsukioka Yoshitoshi, Japanese - The Demon Omatsu Murders Shirosaburō in the Ford - Google Art Project.jpg, A man killed by a woman when carrying her piggyback in the river. File:Piggyback by the trainload rather than one wagon at a time is more efficient.gif, Piggyback by trainload concept File:The End (for now) (6265367138).jpg, Trailers on flatcars in the United States

References

External links

Double Piggyback p120

{{DEFAULTSORT:Piggy-Back (Transportation) Transport operations Intermodal transport