Catch sidings are provided in the case of hilly terrains, where the gradients near railway stations are very steep. The purpose of catch sidings is to arrest the movement of the vehicles if they start to roll down the grade, which may eventually foul up the running lines. A separate siding is provided outside the station yard so that the vehicles can be collected there.
In Fig. 26.16, DEF is a running line and AB is a dead end siding. BC is the catch siding connected to the dead end siding preferably by the means of a spring-operated point. The catch siding lies on a rising gradient and its length is so designed that the vehicle loses its kinetic energy when it reaches the dead end. Thus the vehicle is protected from damage and the safety of the trains on the running line is ensured. There is a sand hump provided at the end of the catch siding to prevent any minor damage to the vehicle.
In the case of hilly terrains, normally one siding is provided at each end of the station as explained here.
Catch sidings These are provided at the higher level or upper end of a station when it starts to slope downwards along the track in an unauthorized manner from the previous station.
Slip sidings These are provided at the lower level on the lower end of the station. If by chance the vehicle is not caught in a catch siding and enters the station premises, the same will be caught and shipped into the slip siding.
Clapham Junction (London) of the Southern Region on British Railways is probably the greatest junction station in the world. It has 17 platforms but 12 of these lines are used by trains that either make only an ordinary station stop or do not stop at all. The other five platforms are used for miscellaneous purposes and are chiefly provided for trains transporting milk and other similar articles, which require a significant stop before the lines can be cleared. Thus, as many as 2500 trains can
run daily with ease from this station, as very few trains occupy the platform for more than a minute or so.
Stations and yards are provided to control the movement of trains, passengers, and goods. Stations are classified based on their operational and functional characteristics. The facilities to be provided at a station depend upon the type of station it is. Similarly, yards are also classified as coach yards, goods yards, marshalling yards, or locomotive yards depending upon their purpose. The efficiency of a station largely depends on the efficiency of its yards.
1. (a) What are marshalling yards and where are they usually located?
(b) Enumerate the principal types of marshalling yards and the basic facilities that should be provided with each one of them.
(c) Approximately estimate the yard capacity of a marshalling yard that is required to deal with 1000 wagons a day with an average detention of wagons of18 hours during the peak season. To ensure proper fluidity, assume a suitable yard balance.
2. (a) Name the different types of marshalling yards. With the help of a neat sketch explain how goods train arriving at such a yard from different directions could be rearranged into their proper order.
(b) Explain the following.
(a) Flag station and block station
(b) Island platform and dock platform
(c) Junction and terminal
3. What is the purpose of providing marshalling yards? What are the points to be considered in the design of marshalling yards? What are the main siding features of marshalling yards?
4. What are the functions of a railway station? Explain briefly the various requirements of a railway station at an important city.
5. Draw a diagrammatic and dimensioned layout of a BG three liner crossing station with the minimum provisions for goods handling. Also mark the signals at either end at the appropriate distances. Assume the station to be a B class station with standard III interlocking and 70 wagons loop capacity.