Hump yard
railroad yard found at some freight train stations used to separate railroad cars over a track upon an artificially built hill (hump) onto different tracks for each direction using gravity. Cars are brought to the top of the hump and by gravity can be automatically assigned into the classification tracks.
Freight trains which consist of isolated wagons must be composed to trains and divided to their destinations. Thus the wagons must be shunted several times during their way in contrast to e.g. a block train which carries automobiles from the plant to a port or coal from a mine to the power plant. This shunting is done at one part in the starting and final destinations and at the other part for the long-distance-hauling in classification yards.
There are three types of classification yards:
- flat-shunted yards: the tracks lead into a flat shunting neck on one or both ends of the yard where the wagons are either shoved or kicked for sorting them into the right track. There are many medium-sized flat yards in the USA and also someones which are quite large like (Houston-) Settegast, Decatur, East Joliet etc. In Europe several major classification yards in Italy never had a hump such as Verona Porta Nuova, Foggia or Villa San Giovanni (Fascio Bolano); other large European flat yards are e.g. Olten (Switzerland) or Valea lui Traian (Constanţa, Romania -this is an incompleted yard with 32 tracks which was planned to be a hump yard but has no hump). In Argentina all classification yards with the exeption of Villa Maria are flat yards though some of them have ca. 30 and more tracks.
- hump yards: these are the largest and most effective classification yards with largest shunting capacity of several thousands wagons a day. The heart of these yards is the hump: a track on a hill (hump) over which the wagons are shoved by the engine after being uncoupled just before it or on its top (hump crest) and then they are rolling by gravity into their destination tracks in the classification bowl (the tracks where the wagons are sorted). The speed of the wagons rolling down from the hump into the classification bowl must be regulated because the different natural speed of each wagon (full or empty, heavy or light freight, number of axles) and the different filling of the tracks (whether there are actually few or already many wagons within it). Related to the speed regulating there are two types of hump yards: without or with mechanisation by retarders. In the old non-retarder yards braking usually was done by railroaders who layed skates onto the tracks in Europe or by riders on the wagons in the USA. In the modern retarder yards this work is done by mechanized "rail brakes" called retarders. They are operated pneumatically e.g. in USA, France, Belgium, Russia or China and hydraulic e.g. in Germany, Italy or the Netherlands. The classification bowl almost in Europe consists of several balloons with mostly eight classification tracks following a retarder in each one of it, often totally 32 tracks. In the USA in each balloon there are often nine instead of eight tracks in Europe. The world's largest classification yard is a hump yard: Bailey Yard in North Platte, USA. Very large other US hump yards are Elkhart Young Yard, (Chicago-) Clearing, (Kansas City-) Argentine, (Houston-) Englewood, Waycross Rice Yard etc. Specially in Europe (for exceptions [closures] see below), Russia and China all important classification yards are hump yards. Europe's largest hump yard is that of Maschen near Hamburg, Germany; it is only a few smaller than Bailey Yard. Most hump yards are single yards with one classification bowl but some, mostly very large, hump yards have two of them, thus are double yards, such as Maschen or Bailey yards. But due to transferring the freight transport from rail to road and containerization of railfreight transport for economical reasons hump yards generally are in decline. So in Great Britain, Denmark, Norway, Japan and Australia all hump yards already have been closed.
- gravity yards: they are operated similar as hump yards but in contrast to them the whole yard is layouted in a continuous falling gradient and there is only less use of shunting engines. Typical locations of gravity yards are there where it was difficult to build a hump yard due to the topography. Most gravity yards have been built in Germany and Great Britain, additionally someones in some other European countries. In the USA there have been only very few old gravity yards, I do not know of anyone in operation today. Largest active gravity yard is Nürnberg (Nuremberg) Rbf (Rbf: Rangierbahnhof [classification yard]), Germany. Gravity yards also have a very large capacity but they need more staff than hump yards and thus they are the most uneconomical classification yards.
Bibliography
- International Railway Journal (IRJ), New York. Special editions about hump yards in various countries: issues II/66, II/70, VI/75, II/80.
- RHODES Dr. Michael: The Illustrated History of British Marshalling Yards. Sparkford: Haynes Oxford Publishing & Co, 1988. ISBN 0-86093-367-9. Out of print.
- KRAFT Dr. Edwin: The Yard: railroading's hidden half. In: Trains (vol. 62) 2002. Part I: VI/02, pp. 46...67; part II: VII/02, pp. 36...47.
- WEGNER Robert: Classification yards. Map of the Month. In: Trains IV/2003, pp. 42/43.
- RHODES (Dr.) Michael: North American RAILYARDS. St. Paul (USA): Motorbooks International (MBI Publishing Company) 2003. ISBN 0-7603-1578-7.
For further informations please see this international quadrilingual site: .
