In Automatic signalling territory, trains shall run in the established direction of traffic only, which means, for example, on most double line, down trains on down line and up trains on up lines are only allowed; (Most in the sense that there are some double line sections in Indian Railway where both up or down train are permitted to run simultaneously; for example, Mau jn. ~ Indara jn. section in NER). Movement of trains against the established direction of traffic is not permitted.
When in an emergency it becomes unavoidably necessary to move a train against the established direction of traffic, this shall be done only under special instructions which shall ensure that the line behind the said train upto the...
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station in rear is clear and free from obstruction.

When the train is unable to proceed further due to unusual occurrences like floods,
breaches, accidents etc., the following procedure shall be followed:
1. the train shall be protected in rear
2. inform Station Master in advance or Station Master in rear or SCOR or TPC and obtain
permission only from Station Master in rear to push back,
3. such permission can be given only by Station Master of the block station in rear provided
that no train has been despatched behind this train,
4. the said permission can be obtained by establishing telephone contact or by sending a
competent railway servant. If telephonically contacted, Station Master in rear shall give a
Private Number. If the competent railway servant is sent, Station Master in rear shallgive a Caution Order permitting pushing back of the train. He shall also intimate the Station Master at the other end about the occurrence.
5. before authorising the movement, the SM shall ensure that the LC gates, if any, are closed against road traffic. The Loco Pilot, after obtaining permission form the Station Master
in rear as above, shall follow the rules and proceeds.

Source : G&SR Railway