Adapted from Coyle, J.J., E.J. Bardi and R.A. Novack (1994) Transportation,
Fourth Edition, St. Paul/Minneapolis: West Publishing Company, p. 262.
Piggyback and Doublestack Train Cars
One of the first attempts at piggybacking dates back to 1872 when
the Barnum & Bailey Circus used its own special train of flat railroad
cars to tour cities in the United States. It took 3 to 5 hours and considerable
effort to unload and load trailers, but the concept remained and piggybacking
started to be adopted by railroad operators. By the 1950s piggybacking
became increasingly used and a good source of income for rail companies.
Containerization however changed from piggybacking to stacking and then
to doublestacking where possible. Doublestacking of containers (Container
on Flat Car; COFC) saves much more convoy space than the piggyback method
(Trailer on Flat Car; TOFC) with the added advantage of not to have
to carry a trailer. However, several rail routes are not compatible with
doublestacking because of the required height clearance for bridges
and tunnels (5.5 meters). Converting a rail line to doublestacking can
be a costly undertaking, especially on the much older European rail
system where bridge clearances tend to be lower. In North America, such
investments are done over high priority corridors.