Piggyback (transportation)

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Piggyback transportation is transportation of goods where one transportation unit is carried on the back of something else - it is a specialised form of intermodal transportation and of combined transport.[1]

Etymology[edit]

Piggyback is a corruption of pickaback, which is likely a folk etymology alteration of pick pack (1560s), which perhaps is from pick, a dialectal variant of pitch (v).[2]

Examples[edit]

Rail[edit]

Trailers on flatcars in the United States
trucks on a train

In rail transport, the practice of carrying trailers, or semi-trailers in a train atop a flatcar is referred to as "piggybacking."[3]

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. A related transportation method is the rail transport of semi-trailers, without road tractors, sometimes referred to as 'Trailer on Flatcar' (TOFC).

It is also possible to carry a railway wagon of one track gauge on a flat railway wagon (transporter wagon or rollbock) of another gauge; indeed, whole trains of one gauge can be carried on a train of flat wagons of another gauge as was done temporarily in Australia for about a year around 1955 between Telford and Port Augusta.[4][5]

The loading of semi-trailers in the U. S. grew from 1% of freight in 1957 to 15% in 1986.[6]

Marine[edit]

Small ships of all kinds can be piggybacked on larger ships. Examples include lifeboats, landing craft, minesweepers on motherships.[7] Midget submarines on big submarines such as used for 1942 Japanese submarine attack on Sydney.

Air transport[edit]

The 1930s British Short Mayo Composite, in which a smaller floatplane aircraft, the four-engined "Mercury", was carried aloft on the back of a larger four-engined flying boat named "Maia"; this enabled the Mercury to achieve a greater range than would have been possible had it taken off under its own power. In space transportation systems a smaller satellite that is carried as a secondary payload on a launch is said to be "piggybacked" on the main launch.

Military[edit]

The metal caterpillar treads of a tank wear out quickly when travelling long distances on ordinary roads. It is therefore necessary to provide tank transporters, which have rubber tires, to the battlefield.

Gallery[edit]

Timber wagon on rollbocks 
S.20 Mercury atop Maia 
Bonn–Oberkassel train ferry 
Rolling road 

See also[edit]

References[edit]

  1. ^ Pearlman, Robert Z. (7 September 2012). "Shuttle Endeavour to get one last piggyback ride across US". MSNBC. Retrieved 24 October 2012. 
  2. ^ Harper, Douglas. "piggyback". Online Etymology Dictionary. Retrieved 24 October 2012. 
  3. ^ THE GEOGRAPHY OF TRANSPORT SYSTEMS
  4. ^ Trove - Pick-a-back operation solves gauge-break problem, 1955 / Adelaide Advertiser
  5. ^ Uniform Eailway Gauge, E. Harding, Lothian Publishing Co., 1958
  6. ^ [Alexander J.] Check |authorlink= value (help) (2011). A Great Leap Forward: 1930s Depression and U.S. Economic Growth. New Haven, London: Yale University Press. p. 114. ISBN 978-0-300-15109-1. 
  7. ^ "Mine-Sweepers By "Piggyback"", The Mercury (Hobart), 5 June 1951: 5 

External links[edit]