Q. How can a temporary diversion to laid a cross flowing river in case of disruption to rail traffic over a major bridge lasting over 6 months.
Ans.-
Temporary diversion constructed around an obstruction to traffic and not likely to be in use for more than 10 days.
In case of disruption to rail traffic over a major bridge lasting over 6 months the semi permanent diversion should be laid to the following specification as for as possible -
In this case temporary diversion not to be laid.
i. Radius of curve - Not less than 450 m.
ii. Gradient - Not steeper than 1 in 100.
iii. Super elevation - Normally no super elevation is provided but if it is provided it should be limited to suit the speed permitted over the diversion and run out at a rate not exceeding 12 mm in 10 m.
In addition to above specified standers for semi permanent diversion are as under -
i. The existing bank should not be cut to lay diversion.
ii. The gradient should be suitably compensated for curvature in order to ensure that in spite of the curvature the gradient does not exceed the limiting value.
iii. If a bridge is on diversion with cribs a straight 7 level portion of 30 m should be provided on either approach of the bridge.
iv. To guard the diversion against possible settlement provide a blanket and roll it if possible.