Piggyback (TOFC) and Doublestack (COFC) Train Cars

Piggyback and Doublestack Train Cars

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.

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 having 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 were done over high-priority corridors. Additionally, the standard trailer size in North America grew to 48 feet and then 53 feet, changing the dynamics and the economics of piggybacking. As a result, TOFC services have been mostly replaced by COFC services.