A train yard is the heart of any city's or company's rail transportation. There are several different varieties of yards catering to different types of trains and cargo. The purpose of each one is to accept incoming cars, remove specific cars, attach cars to another train, and send the trains down the appropriate track.
In addition to dividing up cars and changing direction, train yards are also havens for repair. Most large train yards will feature several machine shops catering to the various needs of a train. Many yards also have large stock yards that allow trains carrying animal cargo to unload. Most yards will be home to a variety of engineers, firemen, brakemen, conductors, and railroad officials who often inhabit large onsite offices too.
From the outside, the entire operation may look confusing. A large train yard is normally the size of several football fields, all with tracks leading in every direction with trains constantly coming and going. A yard is really a well organized, highly orchestrated place of business that can handle several thousand cars a day.
No matter what volume of traffic they see, a train yard will fall into one of three classifications: flat-shunted yards, hump yards or gravity yards. A flat-shunted yard is the most traditional, featuring a flat stretch of land with all the various tracks leading to a bottleneck at each end of the property. Cars here must be pushed by shunting engines onto the proper track to be linked up with new trains.
Hump yards are quite different, and serve as an achievement in train yard efficiency. These are categorized by the large elevated hump of tracks in the center of the yard. This allows for cars to be unlocked and rolled to their destination by gravity and momentum instead of being pushed by another engine.
Gravity yards are considered to be the least efficient yard of all. In this type of train yard, all of the tracks are built on a gradient and require a large staff to ensure each car gets to its destination train. The majority of gravity yards are located in mountainous European nations where there is not enough level land for a hump or flat-shunted train yard.
Train yards are an essential component in rail transportation. No matter the type, they are the central nervous system that sorts out and fixes any problems with the complex world of rail travel.