Classification Yard

A classification yard is a railroad yard in which freight cars are sorted, or classified, according to where they need to go next and assembled into outbound trains. It is one of the central facilities in freight railroading, the place where the cars of many inbound trains are taken apart and recombined into new trains bound for various destinations.

How It Works

Inbound trains arrive and are broken up so that each car can be routed to a track set aside for a particular destination, block, or outbound train. A class code tells the yard where a car is headed next, and the yard uses that information to decide which track to sort it onto; the code itself does not dictate the track. The cars are then switched onto those tracks, where they accumulate until enough cars are gathered to build a departing train. Once a track holds a complete block or train, the cars are pulled together, a locomotive is attached, and the new train departs on its line-haul movement.

Flat Yards and Hump Yards

Classification can be done in different ways. In a flat yard, switch engines push and pull cuts of cars to sort them across the tracks. In a hump yard - more formally an automated classification yard - a locomotive shoves cars over a small hill, where they are uncoupled and roll by gravity onto their assigned tracks, with computer-controlled switches and retarders managing routing and speed. In either case, the purpose is the same: to turn the mixed cars of arriving trains into properly built departing trains.