gauge freight lines were closed in the 1980s. Special adaptors could be employed to couple a set of transporter wagons onto the end of an "ordinary" narrow gauge freight train. Continuous braking was no problem, either, as the train air line could be incorporated into the bar couplers, too. Judging from early literature, the transporter wagon idea came about in Germany sometime around 1880 or 1890 (where in fact, later, Rollböcke were used a lot more than transporters). Transporter wagons with the unique Heberlein type friction brake system were in daily use in the old GDR (East Germany) well into the late 1980s. In Britain, they were introduced to the Leek and Manifold Valley Light Railway in 1904 by Everard Calthrop, who also introduced them to the Barsi Light Railway in India of 1897. They carried the bulk of the freight traffic on the Leek and Manifold Valley. Transporter wagons are widely used to get rolling stock including locomotives from gauge-isolated branch lines to main maintenance centres. Crocodile wagons The South Australian and Victorian Railways used broad gauge transporter wagons to carry narrow gauge rolling stock and locomotives to workshops and other isolated narrow-gauge sections. In South Australia, these were called crocodile wagons. The GWR also had crocodile wagons. One is in the Didcot Railway Centre Transporter train in Australia In 1955, during an intermediate phase of the replacement of the narrow-gauge () Port Pirie to Marree railway with a standard gauge line, train-lengths of standard-gauge flat wagons were fitted with narrow-gauge rails, allowing narrow-gauge trains carrying coal (from Leigh Creek coalfield), livestock or general freight to travel more quickly by standard gauge on the new, well-engineered alignment. The rails on the flat wagons were continuous, so that the upper train could be rolled on and off in one piece. The leading wagon on the narrow-gauge train was also secured to anchoring on the front wagon on the standard gauge train. Air brakes on the narrow-gauge train were connected to the standard-gauge train's air brakes. A narrow-gauge locomotive pushed the narrow-gauge train up an earthen ramp to the deck of the standard gauge train. There were no overhead structures to restrict operation of the trains. Train on Train "Train on Train" was a Japan Railways concept, similar to the South Australian scheme above, for hauling narrow-gauge container wagons at speeds of up to on standard-gauge Shinkansen track through the long,