It is called "Road Train" ..

A road train or roadtrain is a trucking concept used in remote areas of Argentina, Australia, Mexico, the United States and Canada to move freight efficiently. The term "road train" is most often used in Australia. In the U.S. and Canada the terms "triples," "turnpike doubles" and "Rocky Mountain doubles" are commonly used for longer

combination vehicles (LCVs). A road train consists of a relatively conventional tractor unit, but instead of pulling one trailer or semi-trailer, a road train pulls two or more of them.
On February 18, 2006, an Australian built Mack truck with 112 semi-trailers, 1,300 t (1,279 long tons; 1,433 short tons) and 1,474.3 metres (4,836 ft 11 in) long, pulled the load 100 metres (328 feet) to recapture the record for the longest road train (multiple loaded trailers) ever pulled with a single prime mover. It was on the main road of Clifton, Queensland, that 70-year-old John Atkinson claimed a new record, pulled by a tri-drive Mack Titan