A classification yard , marshalling yard (British, Hong Kong, Indian, and Australian English, and the former Canadian Pacific Railway) or shunting yard (Central Europe) is a railway yard used to accumulate railway cars on one of several tracks. First, a group of cars is taken to a track, sometimes called a lead or a drill. From there, the cars are sent through a series of switches called a ladder onto the classification tracks. Some larger yards may put the lead on an artificially built hill called a hump to use the force of gravity to propel the cars through the ladder.
Freight trains that consist of unrelated cars must be made into a train grouped according to their destinations; this shunting is done at the starting point. Some trains drop and pick up cars along their route in classification yards or at industrial sidings. In contrast is a unit train that carries, for example, automobiles from the plant to a port, or coal from a mine to the power plant.