GATX Intermediate TankTrain Cars First built in the 1970s, the TankTrain system provided a faster, more economical way to load and unload unit trains of tank cars. Strings of these cars were connected with hoses and valves. Rather than handling each car individually, a crew could load or unload the entire string from one end of the train. Like our other Standard O rolling stock, these tank cars feature prototypical detailing and feature many separately applied metal details, including flexible hoses between the cars. These new TankTrain cars are a perfect addition to the TankTrain set.