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Ragnar's HO Model Trains Weeb Site |
| Yards |
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Ragnar's HO Model Trains Weeb Site |
| Yards |
One of my favorite aspects of railroads is the track, and the panultimate hight of track laout is the YARD. I love rail yards :o)
CLASSIFICATION RAILROAD YARDS or switching
A YARD is described as "a system of tracks within defined limits provided for making up trains, storing cars and other purposes, over which movements not authorized by timetable or by train order may be made, subject to prescribed signals and regulations."
Most large yards are made up of several smaller yards. The receiving yard is for receiving inbound freight trains. The classification yard is where cars are sorted and rearranged. The type of classification yard illustrated is a "hump yard," where cars are pushed over a steep incline beyond which they run by gravity into various tracks. In a "flat yard" the cars are pushed or pulled into proper order by locomotives. The departure yard is where sorted cars are stored until the time of departure as trains. The caboose track is a storage track. There also may be a storage yard for empty freight cars. This particular yard has a car cleaning section, and most yards of any size have a track or several tracks where minor repairs are made.
Engine facilities are usually located close to the freight yard. This example also has a through-train and icing yard. Many old refrigerator cars had hatches in the roof where ice was added to keep the interior cold. All refrigerator cars now in interchange service have mechan- ical refrigeration, so the icing plants have disappeared.
While this example shows a very large yard with sections for various purposes, most yards are much smaller; yet many of the same operations have to be carried out in them, except on a smaller scale. For example, in an eight-track yard, a track at one side might be used for occasional car repairs, while a track near the middle might be used as a through track. Classification and stor- age would be done on other tracks more or less interchangeably.
Prototype yards often have ladders at each end to all tracks, but in model railroading this requires a large amount of space. It is better for model yards to have just two or three double-ended tracks with the rest stub-ended. Notice in the second illustration how much longer the first two yard tracks can be because they do not connect into the ladder at the left of the diagram.
Modelers have long been fascinated by railroad freight yards, so a common pitfall is for modelers to design and build yards that are too large in relation to the rest of their pikes and to use them simply for storage. The value of a freight yard-model or prototype-is not measured by how many cars can be stored in the yard, but by how smoothly and effi- ciently cars en route to and from their des- tinations can be processed in the yard.
Two important variables which govern yard size are the number of cars in use at one time on the layout and the capacity of the industrial spurs and sidings. Ideally, the yard should be able to hold more than the difference between these two. If the yard is filled to capacity, switching, making up, and breaking up trains becomes impossible. Spurs should not be filled to capacity, either.
Yard tracks do not have to be straight, but any curves used in the approaches should be gradual; if they are not, coupling and uncoupling problems may be introduced. Ideally, a curve should have easements (a transition curve of increasing radius between the straight track and the main curve) at both ends and have a radius equal to about seven to eight times the average length of car that will use it. A gentle curve about midway down the yard can introduce a pleasant scenic effect.
Yard track definitions
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© Ragnar Torfason 2006 March 28 | |