Diversion

(1) General – Should a diversion be decided upon, the work should be commenced as quickly as possible.

(2) Classification of diversions – These may be classified as – 

(a) Temporary                                                                          (b) Semi-permanent

A temporary diversion is one which is not likely to be in use, for more than 10 days. All trains must “Stop-dead” before entering a temporary diversion and proceed at 10 Km./h. speed.

A semi–permanent diversion, is one constructed for the special purpose of facilitating the reconstruction of the line and/or bridges likely to be in use for a period of more than ten days. On a semi-permanent diversion, trains may proceed at a non stop reduced speed after adequate period of consolidation.

(3) Curvature and Gradients – As far as possible the radius of curve should not be less than 450 meter, 300 meters and 45 meters for B.G.,M.G., and N.G., respectively. Gradient should not be steeper than 1 in 100, 1 in 80 and 1 in 40 on

the B.G., M.G. and N.G. respectively, compensated for curvature. In difficult terrain it may be necessary to lay curves of radius not less than 225 meters and 125 meters on B.G. and M.G. respectively and adopt grades up to the ruling gradient on the section. There should be no superelevation, in case of temporary diversions.

(4) Calculation for setting out diversion –While setting out diversion, the following formula will be found handy :–

where

AB = Portion of existing line to be diverted.

L = Length of half the diversion, measured along the original alignment.

D = Maximum distance of diversion from original alignment.

S = Straight portion of diversion.

C = Length of straight between reverse curves.

R = Radius of curves.

T = Length of tangent.

(5) Opening for traffic – The diversion track should be adequately consolidated and tested by locomotive/ wagons before opening for traffic. The most vulnerable portion of the diversion is at the junction of the old bank with the new bank. Care should, therefore, be taken to provide benching of slopes at the junction. Cross levels should be checked after passage of every train and rectified till the track gets stabilised.

(6) Issue of safety certificate – In an emergency the line may be opened to traffic on the safety certificate issued by the Engineer-in-charge, without the prior sanction of the C. R. S. However if the use of temporary diversion is likely to be extended to more than three days, the Commissioner of Railway Safety, may if he considers it necessary, take the earliest opportunity of inspecting it.

Transhipment – 

The decision, as to whether transhipment is to be done, is taken by Transportation/Commercial Department. If it is decided to provide gangways,

footpath etc., purely for the purpose of transhipment, these should, as far as possible, be laid away from the site of repairs, so that the progress of restoration is not interfered with.

Flooded Causeways / Dips –

(1) Permissible depth of water for passage of trains – In the case of causeways that are flooded and the velocity of current is insignificant, trains may be permitted to pass when the depth of water above rail-level does not exceed the following values, provided in each case Permanent Way Inspector has satisfied himself by walking over and probing that Permanent Way is intact and in a fit condition :–

(2) (a) Indication posts – Indication posts about 1200 mm. in height shall be fixed at each dip, one at each end of the level portion, with flat bar attached to them to indicate level mentioned.

(b) The posts should be painted black and white in 300 mm. length so arranged that the flat bars which shall be painted white, show up against 300 mm. length of black colour

(c) The posts shall be fixed 3 metres from the centre of the track in the case of Broad Gauge and 2.5 metres from the centre of track in the case of Metre and Narrow Gauge.

(3) In the section where electric locos/stock and or diesel locos ply, special gauges may be provided by the administration at the place liable to flooding, indicating the depth at which these locos/ stock have to be stopped from the operation. These depths should be specified for each type of locos/ stock by the administration.