Piggyback (transportation)

[3] In the modern era, wife carrying competitions, where the female participants ride on the back of their male partners running the race, are popular in some countries.

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

A saddle is placed on the fifth-wheel, that the front axel of the next truck is attached to, which is called decking.

The 1930s British Short Mayo Composite, in which a smaller, four-engine floatplane aircraft named Mercury was carried aloft on the back of a larger four-engine flying boat named Maia, enabled the Mercury to achieve a greater range than would have been possible had it taken off under its own power.

The metal caterpillar treads of a tank 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).