Source: 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, with the common piggyback load being two 40 foot trailers.
By the 1980s, containerization however changed from piggybacking to stacking and then to doublestacking where possible. Piggybacking became a marginal activity. 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. Additionally, the standard trailer size in North America grew to 48 foot and then 53 foot, changing the dynamics and the economics of piggybacking.