piggyback car

…time, American railroads introduced the piggyback car, a flatcar modified to hold as many as two truck trailers in place. Later piggyback-car designs utilized double-stacked trailers on interconnected flatcars. The two-level and three-level rack cars widely used in the United States and Canada for conveying new automobiles are also examples…

…America was on the rail piggybacking of highway trailers on flatcars (TOFC), which the Southern Pacific Railroad pioneered in 1953. By 1958 the practice had been adopted by 42 railroads; and by the beginning of the 1980s U.S. railroads were recording more than two million piggyback carloadings a year. In…