Rail Yard Basics
Rail yards are often the hubs of rail activity. But what is their function? This article will explore the various types of yards, and their functions.
The Flat Yard
Perhaps the simplest type of rail yard is the common flat yard. The flat yard is just that, a flat yard, with tracks which run parallel to each other, connected by a common ladder track (or 2 common ladder tacks, one at each end). Flat yards can be as small as a simple 1 or 2 track siding used for storing freight cars, to a massive 50 track yard used for classification and sorting. The key to a flat yard is that all the switching is done manually. Thus it is a slow and inefficient method for sorting and classifying cars. In most cases these yards are used as transfer yards between branches or rail carriers, or in industrial areas as staging yards for larger industries. They are also commonly used for regional/local yards.
Flat yards are often very simple, and use track numbering which is also very simple, often starting ‘track 1′ from the closest parallel track from the main line, and working out from there. It is also rare for a flat yard to have more then 2 ladder tracks. Busy yards may have 3 or 4 ladder tracks (two on each side, to allow two classification jobs to work the yard at the same time), however most only have 2 – one on each side. Flat yards also rarely have more then one or two main lobes (groupings). There is almost always a running track in flat yards as well. A running tack is a track which is designated to always be kept clear of stationary rolling stock so as to allow rains to pass through the yard within the yard limits. Note that this is not the same as a mainline track which may parallel the yard, as to use the main line would require leaving the yard limits in most cases.
A Hump Yard is a modern sorting facility. Think of a Hump Yard as a grand terminal of freight. This is where most modern freight gets sorted and classified. Every major city has at least one Hump Yard near it, as a general rule of thumb - but as railroads modernize and streamline their operations, they have been eliminating smaller and less productive hump yards where possible.
The Hump Yard is actually a combination of flat yards and hump yards alike to create a flowing system. Often there will be a group of receiving tracks which will consist of a flat yard where trains can pull into.
The locomotives of these trains will detach from their consist, and often will head to a locomotive facility for refueling and reassignment. The locomotive shop is also another aspect of most hump yards, and is a small flat yard used for servicing.
A local yard switcher will connect to the consist of cars that the incoming train left on the receiving tracks, and then will direct it to a ‘hump’ which is where the train will be sorted into new trains. The switcher pushes the string of cars over the hump, which is often a small hill. Gravity propels the cars down the hill and into an electrically controlled yard. Switches at the mouth of the hump yard are operated remotely, often with the aid of a computerized system which knows what track the next car needs to be in. The car, now free of its former train, rolls into the correct track in the classification bowl to be included in a train to its new destination. Devices called Retarders, which are actually stationary breaking systems build into the track, at the mouth of the hump yard, slow the loose cars down to a safe speed as they roll towards their destination track. This is actually the hump of the hump yard.
From there, a yard switcher will take a string (or rake) of cars out of the classification bowl (hump yard) and place them into a departure yard. The departure yard is another long flat yard, which is where outgoing trains are assembled from strings of cars made in the classification yard.
In some cases, yards will have more then one hump yard, to serve either local and long haul service, or to serve eastbound and westbound traffic. If this is the case, these yards will often have separate receiving and departure yards for each. It is also common to have a yard within a hump yard for local traffic, as well as a yard for car storage.
The Intermodal Yard is becoming one of the busiest types of yards on any rail system. Intermodal yards are large spread out flat yards, with cranes and hoists to facilitate the loading and unloading of container (COFC – Container on Flat Car) and road trailer (TOFC – Trailer on Flat Car) loads from specially constructed flat cars.
The key to Intermodal operations is that you can completely avoid humping and classifying for the most part. Trains just run from one Intermodal yard to another, usually as high priority trains, and local loads are removed and sent by truck to their destination. The rest of the train remains in place and is sent off to another destination. This streamlines operation. And while this type of operation kills the classic style of freight railroading we all grew up to enjoy watching, this is one of the biggest money makers in the freight world, and thus it keeps the trains rolling.
The Auto Yard
An Auto Yard is often a flat yard with a single ladder track on one side. Ramps set at the dead end of each track facilitate the loading and unloading of automobiles into autorack cars. These yards are usually surrounded by a vast sea of new cars in a large parking lot.
That basically covers all of the train yards in use today.