Education - Part 3E2
Railroad Yards
Railroad Yards
A railroad yard is an area where trains or parts of trains can be assembled or reassembled (marshaling, classification or sorting yard), stored (storage yard), maintained (maintenance or repair yard) or loaded/unloaded. Large railroad yards will usually be subdivided into an arrival yard, a classification yard, an assembly yard and a departure yard (and possibly others).
Arrival Yard
The arrival yard is the area where a train "parks" upon arrival at the railroad yard. The arrival yard serves several purposes, the most important of which is to clear the main line so as to avoid interfering with the normal flow of traffic. The arrival yard also is where a train is first broken up to allow cars to be classified or sorted. This yard also provides the opportunity to inspect all cars of the train for necessary maintenance and repair. The contents of cars in need of extensive repair may have to be moved to another car. This would involve the loading/unloading yard and then the maintenance yard.
Loading/Unloading Yard
This yard is where goods are either loaded into un-powered cars or are unloaded for transfer to other cars or to ground transportation for transport to final destination. This yard may be situated near manufacturing facilities or shipping facilities such as ports or freight terminals.
Classification or Marshaling Yard
The classification (marshaling, sorting) yard is perhaps the most important, as this is where individual cars (mostly freight), uncoupled from an arriving train, are sent to a branch line consisting of cars to be delivered to a particular destination, cars carrying a particular product, cars that must be maintained, cars destined for storage and so on. Here is a video (1:27 minutes) and a second video (4:35) that illustrate the classification process.
Cars also may be sorted by owner, by weight (empty, light-weight goods, etc.), by type (flat, tank, hopper, etc.), by goods, by destination (drop-off or final), by route (specific cars may not be suited for all routes), or other categories.
Assembly Yard
Once cars are sorted, they may be assembled into one or more trains in the assembly yard. For example, a group of cars may be attached to a unit train (see What Is a Train, above) going to either an intermediate drop-off point or to the same final destination. Otherwise, one or more groups of sorted cars may be assembled into a train headed by the appropriate motive power.
Maintenance Yard
Any powered or unpowered cars in need of maintenance are moved to the maintenance yard. Here one may find a round house and perhaps several buildings focused on performing various types of maintenance such as truck (bogie) repair or replacement, brake work and car body repair. In the case of under-body work, a building with a "grease pit" provides space for workers to service otherwise hard-to-reach parts.
Unit Yard
Where traffic necessitates, a railroad yard may also have a unit yard where unit trains may park for crew changes, servicing and perhaps inspection for problems. Unit trains do not undergo classification (why?).
Storage Yard
A storage yard serves to hold rolling stock when not in use. Life in the storage yard should be brief, since cars sitting idle produce no revenue.
The storage yard may be subdivided into areas by type of car so as to facilitate retrieval of a specific type of car when needed.
Yard Structure
Railroad yards originated as flat yards in which cars were moved around using switching or shunting locomotives. Later, yards were sometimes built on land that had a useful slope (gravity yard). In this way, gravity could be used to move cars, thus saving the cost of switching locomotives. However, workers were still required to operate hand brakes to prevent cars crashing into one another and causing damage.
Major railroad yards are built around the hump concept (hump yard). A large mound or hump is constructed so a car pushed over the hump can be directed under gravity power to a classification yard. A hump may be as high as 10 meters (32.8 feet). A car is moved from the arrival yard, by means of a switching locomotive, up the hump and released. The car then moves under gravity power and a control tower directs the car to the correct siding in the classification yard. Retarders along the descending track(s) control the velocity of the car as it travels to a specific track where other cars of the same class are waiting.
Railroad yards originated as flat yards in which cars were moved around using switching or shunting locomotives. Later, yards were sometimes built on land that had a useful slope (gravity yard). In this way, gravity could be used to move cars, thus saving the cost of switching locomotives. However, workers were still required to operate hand brakes to prevent cars crashing into one another and causing damage.
Major railroad yards are built around the hump concept (hump yard). A large mound or hump is constructed so a car pushed over the hump can be directed under gravity power to a classification yard. A hump may be as high as 10 meters (32.8 feet). A car is moved from the arrival yard, by means of a switching locomotive, up the hump and released. The car then moves under gravity power and a control tower directs the car to the correct siding in the classification yard. Retarders along the descending track(s) control the velocity of the car as it travels to a specific track where other cars of the same class are waiting.
Major Yards
There are many railroad yards around the world. The largest of these is the Union Pacific Bailey Yard located in North Platte, NE. This yard covers 4.5 sq mi; 11.5 sq km) and is over 8 miles (13 km) in length and 2 miles (3.2 km) wide at its widest point. The yard has about 200 separate tracks totaling 315 miles (507 km) of track, 1,751 turnouts (switches) and 17 receiving and 16 departure tracks. The Bailey Yard handles an average of about 140 trains/day with some 14,000 non-powered cars. The yard has two humps and sorts or classifies some 3,000 cars/day (maximum capacity is about 5,800 cars/day. The yard has facilities for servicing trains as they pass through and can also repair both locomotives and non-powered cars.
The second largest railroad yard, DB Cargo AG - Werk Maschen, is located in Seevetal, Germany, south of Hamburg. It is operated by Deutsche Bahn (DB).
The following illustration shows the Conway Yards of Norfolk Southern (NS), also a quite large yard, that is located in Conway, PA along the Ohio River about 25 miles northwest of Pittsburgh, PA.
A diagram showing the layout of Norfolk Southern's Conway Yards in Conway, PA (the size of the yard necessitates this orientation)
Every railroad has yards of varying size located strategically to facilitate movement of freight (goods). Although railroads are not always able to deliver freight by rail to the final destination (the so-called "last mile") they will have arrangements with other transportation companies to perform this service. Some railroads also own trucking companies for this purpose.