what is catch siding In Indian Railway
In ghat sections it is so required that sometimes the train has to go downslope…and in such a case you can understand the efficiency required for stopping a train in terms of brake.The braking systemmust be highly efficient so that a train can be able to stop itself even in ghat sections.But the problem is that in case a train’s brake system is not well efficient what would happen in such a case??
Indian Railways has adopted a process the technical term for which is CATCH SIDING.In ghat section such point are set at every regular intervals where the cabin man automatically revert the line towards catch and the signal at such point is kept in ón’state.When a train encounters such a point with a signal in ón’state the train has to come to a halt in such downslopes.and the train’s brake is tested and the line is diverted towards main line and the train continues its journey.But when a train cant stop itself in such downslopes then it is automatically diverted towards catch and the catch is such that it automatically bring the train to halt by providing incline or upslope.Thus this is an excellent method adopted by indian railways to avoid accidents in ghat sections.
As per Rules for Opening of a Rly for the Public carriage of passengers (See foot note to item: 44of Form IX) Catch sidings are to be provided if the gradient falling towards a station is steeper than 1 in 80. Similarly Slip sidings are to be provided if the gradient falling away from the station is steeper than 1 in 100. For this it is mentioned that if any station is situated in the immediate neighbourhood of such gradients. It is not clear what is the meaning of immediate neighbourhood?
In CN unit of SW Rly, while designing yard layouts as per CRS’ observations, the general practice followed is that Slip sidings are provided if there is a falling gradient steeper than 1 in 100 within 100 metres from the outermost yard GP. Yards are laid to max. grades of 1 in 400 without any condonation upto a distance of 50m from the outermost top point. If there is no falling grade steeper than 1 in 100 upto 150 m from top point, slip sidings are not provided.
Also as per SOD, if a station yard is constructed on a gradient steeper than 1 in 260 (with condonation from Rly Bd) a slip siding has to be provided on the lower side of the grade to protect the next block section. Normally, slip sidings are provided for 5 vehicle capacity.
Catch sidings are provided to catch trains without injury to passengers or rolling stock, when the train have gone beyond the control of the train running staff. Vertical Parabolic shape is preferred for gravity catch sidings. In such catch sidings, the maximum grade near the end of the sidings should not be steeper than 1 in 10. The length of such catch sidings would be the max. train length in the section + sand hump length at the end. The proper place to take off a catch siding from the main line is at the commencement of a curve and the catch siding would be laid as the continuation of the tangent. Max. curvature permitted in catch siding is 2 degrees. without any SE. Catch sidings should be designed so that the velocity of the uncontrolled train is totally absorbed and the entire train is homed in catch siding.