Editing Classification yard

{{No footnotes|date=April 2022}}
{{Short description|Rail yard used for sorting and assembling rail cars into trains}}
[[File:Godorf Station at Dusk, May 2018.jpg|thumb|Godorf Station, [[Cologne]], Germany]]

A '''classification yard''' ([[American English]], as well as the [[Canadian National Railway]]), '''marshalling yard''' ([[British English|British]], [[Hong Kong English|Hong Kong]], [[Indian English|Indian]], and [[Australian English]], and the former [[Canadian Pacific Railway]]) or '''shunting yard''' (Central Europe) is a [[Rail yard|railway yard]] used to accumulate [[railway car]]s 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 [[Railway switch|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 (rail)|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, [[automobile]]s from the [[Factory|plant]] to a [[port]], or [[coal]] from a [[Mining|mine]] to the [[Power station|power plant]].

==Flat==
<!-- "Flat yard" redirects here. -->
'''Flat yards''' are constructed on ground too flat to allow a free-fall operation. After a push by a locomotive, freight cars coast to their desired location.<ref>{{cite book |last=James T. Kneafsey |title=Transportation Economic Analysis |url=https://books.google.com/books?id=sjJPAAAAMAAJ |publisher=Lexington Books |isbn=0669932116 |page=138 |chapter=Major Problems of Railroad Service |date=1975 }}</ref>

==Gravity==
<!-- "Gravity yard" redirects here. -->
'''Gravity yards''' were invented in the 19th century, saving shunting engines and instead letting the cars roll by gravity was seen as a major benefit, whereas the larger amount of manual work required to stop the rolling cars in the classification tracks was judged to be not that important. Gravity yards were a historical step in the development of classification yards. They were later judged as inferior to hump yards because it became clear that shunting engines were needed anyway (at least in inclement weather like strong winds or icy temperatures when the oil in the bearings became thick) and because manual labor was becoming increasingly expensive. Thus, only a few gravity yards were ever built, sometimes requiring massive earthwork (one example is the first German gravity yard at Dresden). The historic technique of a gravity yard is today partly presented in [[Chemnitz]]-Hilbersdorf gravity yard (museum).<ref>Denkmalpflege in Sachsen, Jahrbuch 2019, Sandsteinverlag, Dresden, 2020.</ref> 

Most gravity yards were built in Germany (especially in the kingdom of [[Saxony]]) and Great Britain (such as Edgehill, 1873),<ref>{{cite book |last=Köpcke |first=Mitteilungen |title=aus dem Bereich des englischen Eisenbahnwesens |publisher=Der Civilingenieur |location=Leipzig |date=1890 }}</ref> a few also in some other European countries, for example [[Łazy]] yard near [[Zawiercie]] on the [[Warsaw–Vienna railway|Warsaw–Vienna Railway]] (in [[Poland]]). In the US, there were very few old gravity yards; one of the few gravity yards in operation today is CSX's [[Readville (MBTA station)#Railroad yards|Readville Yard]] south of [[Boston, Massachusetts]].

==<span class="anchor" id="Hump yard"></span>Hump==
<!-- "Hump yard" redirects here. -->
[[File:UP DO NOT HUMP.jpg|thumb|Not all cars can be sent over a classification hump. This Union Pacific track maintenance vehicle is permanently labeled "Do not hump" because it is not designed to withstand hump sorting.]]

'''Hump yards''' are the largest and most effective classification yards, with the largest [[Shunting (rail)|shunting]] capacity, often several thousand cars a day. They work similarly to gravity yards, but the falling gradient is limited to a small part of the yard, namely the hump. It is the heart of the yard—a lead track on a small hill over which an engine pushes the cars. Single cars, or a block of coupled cars, are uncoupled at or just before the crest of the hump and roll by gravity onto their destination tracks in the area of the yard where the cars are sorted, called the classification bowl.<ref>{{cite magazine |title=ABC's of Railroading: Terms of the Trade |magazine=[[Trains (magazine)|Trains]] |date=June 1991 |page=22 |publisher=Kalmbach Publishing |location=Waukesha, Wisconsin |issn=0041-0934 }}</ref> The first hump in Germany (Leipzig) was built in 1858 and in France (Saint-Etienne) in 1863. 

[[File:Balkenbremse1.JPG|thumb|upright|The [[Retarder (railroad)|retarders]] grip the sides of the wheels on passing cars to slow them down.]]

The speed of the cars rolling down from the hump into the classification bowl must be regulated according to whether they are full or empty, heavy or light freight, varying number of axles, whether there are few or many cars on the classification tracks, and varying weather conditions, including temperature, wind speed, and direction. In regard to speed regulation, there are two types of hump yards—with or without mechanization by [[Retarder (railroad)|retarders]]. In the old non-retarder yards, braking was usually done in Europe by railroaders who laid skates onto the tracks. The skate or [[wheel chock]] was manually (or, in rare cases, mechanically) placed on one or both of the rails so that the treadles or rims of the wheel or wheels caused frictional retardation and resulted in the halting of the railway car. In the United States, riders in cars did this braking. In modern retarder yards, this work is done by mechanized "rail brakes," called retarders, which brake cars by gripping their wheels. They are operated either [[Pneumatics|pneumatically]] or [[Hydraulics|hydraulically]].  Pneumatic systems are prevalent in the United States, [[France]], [[Belgium]], [[Russia]] and [[China]], while hydraulic systems are used in [[Germany]], [[Italy]] and the [[Netherlands]].<ref>{{cite book |title=Rangierdienst A-Z |publisher=VEB Transpress-Verlag |location=Berlin |date=1986 }}</ref>

Classification bowls in Europe typically consist of 20 to 40 tracks, divided into several fans or balloons of tracks, usually with eight classification tracks following a retarder in each one, often 32 tracks altogether. In the United States, many classification bowls have more than 40 tracks, frequently divided into six to ten classification tracks in each balloon loop.

[[File:Proviso hump towerman.jpg|thumb|left|upright|A [[Chicago and North Western Railway|CNW]] towerman operates the retarders at Proviso Yard in [[Chicago, Illinois]] (1943)]]

[[Bailey Yard]] in [[North Platte, Nebraska]], United States, the world's largest classification yard, is a hump yard. Other large American hump yards include Argentine Yard in [[Kansas City, Kansas]], Robert Young Yard in [[Elkhart, Indiana]], [[Belt Railway of Chicago|Clearing Yard]] in [[Chicago]], [[Illinois]], Englewood Yard in [[Houston]], [[Texas]], and Waycross Rice Yard in [[Waycross, Georgia]]. Notably, in Europe, Russia, and China, all major classification yards are hump yards. Europe's largest hump yard is that of [[Maschen Marshalling Yard|Maschen]] near [[Hamburg]], Germany; it is only slightly smaller than Bailey Yard. The second largest is in the port of [[Antwerp]], Belgium. Most hump yards are single yards with one classification bowl, but some, mostly very large, hump yards have two of them, one for each direction, and thus are double yards, such as the Maschen, Antwerp, Clearing, and Bailey yards.{{Citation needed|date=April 2023}}

Almost all gravity yards have been retrofitted with humps and are worked as hump yards. Examples include [[Chemnitz]] Hilbersdorf (today [[Saxon Railway Museum]]), Dresden Friedrichstadt and Nürnberg ([[Nuremberg]]) Rbf (Rbf: ''Rangierbahnhof'', "classification yard"), in Germany.
{{clear}}

==Unique locomotives==
[[File:Master and slave, Tinsley Marshalling Yard (geograph 5493909).jpg|thumb|British Rail Class 13 built for a hump yard]]{{Section rewrite|date=October 2024}}
Hump yards sometimes require unique locomotives, for example, where larger frames may ground. For this and other reasons, one can sometimes find locomotives specifically made or converted to work a hump yard. For example, the [[British Rail Class 13]] was converted from a pair of [[British Rail Class 08]] to provide more power than one could get with a single Class 08. The class 13s were built because of the risk of grounding with larger units like the [[British Rail Class 20]].<ref>{{cite magazine |editor-last=Bickerdyke |editor-first=Paul |title=Class 13 Tinsley Shunters |magazine=Rail Express |date=October 2015 |issue=233 |page=25 |publisher=Mortons Media Publishing |location=Horncastle |issn=1362-234X }}</ref> Special locomotives for hump yards in the US were for example the EMD TR family ([[EMD TR]], [[EMD TR1]], [[EMD TR2]], [[EMD TR3]], [[EMD TR4]], [[EMD TR5]] and [[EMD TR6]]). These are often referred to as ''[[Cow–calf|master and slave]]'' in GB and ''cow–calf'' in the US.<ref name=":4">{{Cite book |last1=Solomon |first1=Brian |url=https://books.google.com/books?id=BOfUBAAAQBAJ&dq=Cow-calf+switcher&pg=PA37 |title=Chicago: America's Railroad Capital: The Illustrated History, 1836 to Today |last2=Blaszak |first2=Michael |last3=Gruber |first3=John |last4=Guss |first4=Chris |date=2014-10-14 |publisher=Voyageur Press |isbn=978-0-7603-4603-7 |pages=37 |language=en}}</ref><ref name=":3">{{Cite book |last=Foster |first=Gerald L. |url=https://books.google.com/books?id=ZvSHlCxuyH0C&dq=Cow-calf+switcher&pg=PA10 |title=A Field Guide to Trains of North America |date=1996 |publisher=Houghton Mifflin Harcourt |isbn=978-0-395-70112-6 |pages=10 |language=en}}</ref><ref>{{cite book |last1=Smith |first1=Keith |title=Supplement to the West Somerset Railway Stockbook |date=1999 |publisher=West Somerset Railway Association |location=Bishops Lydeard |page=9|edition=5th }}</ref><ref>{{cite book |title=Industrial Locomotives |date=1982 |isbn=0-901096-44-X |page=232 |edition=6EL |publisher=Industrial Railway Society}}</ref>

==Image gallery==
<gallery mode="packed" heights="200">
File:Kornwestheim Ablaufberg 20060318.jpg|A [[switcher locomotive]] pushing a car over the hump at Kornwestheim yard
File:MannheimRangierbahnhof 2018-08-10 Luftbild.jpg|[[Mannheim Rangierbahnhof]], Germany, two-sided nearly symmetrical systems for opposing directions
File:Trainyard.bradleygee.jpg|North Yard in [[Denver, Colorado]], a typical U.S. classification yard in 2009
File:CNW yard, Chicago.jpg|[[Chicago and North Western Railway]]'s Proviso Yard in [[Chicago, Illinois]], December 1942
File:201805 Nanxiang Station Yard III.jpg|[[:zh:南翔站 (京沪铁路)|Nanxiang Classification Yard]] in Shanghai, China
</gallery>

==See also==
* [[List of rail yards]]
* [[Siding (rail)]]

==References==
{{Reflist}}
{{Refbegin}}

==Further reading==
*International Railway Journal (IRJ), New York. ''Special editions about hump yards in various countries:'' issues II/66, II/70, VI/75, II/80.
* {{cite book |last=Armstrong |first=John H. |title=The Railroad: What It Is, What It Does |edition=4th |publisher=Simmons-Boardman |location=Omaha, Nebraska |date=1998 |isbn=978-0-911382-04-4 }}
* Rhodes, Michael: ''The Illustrated History of British Marshalling Yards.'' Sparkford: Haynes Oxford Publishing & Co, 1988. {{ISBN|0-86093-367-9}}. Out of print.
* Kraft, Edwin: ''The Yard: Railroading's Hidden Half.'' In: [[Trains (magazine)|Trains]] (vol. 62) 2002. Part I: VI/02, pp.&nbsp;46–67; Part II: VII/02, pp.&nbsp;36–47. {{ISSN|0041-0934}}.
* Wegner, Robert: ''Classification yards. Map of the Month.'' In: Trains IV/2003, pp.&nbsp;42–43.
* Rhodes, Michael: ''North American Railyards.'' St. Paul (US): Motorbooks International (MBI Publishing Company) 2003. {{ISBN|0-7603-1578-7}}.

{{Refend}}

==External links==
{{Commons category|Classification yards}}
* [https://www.youtube.com/watch?v=6nz-n49pIFQ Time-lapse video of German hump-shunting yard operation]

{{Rail tracks}}
{{Railway track layouts}}
{{Authority control}}

[[Category:Articles containing video clips]]
[[Category:Rail yards]]
[[Category:Railway sidings]]
[[Category:Railway stations by type]]