Section 218(5)(h) in The Dedicated Freight Corridor Railway General Rules, 2018
(h)once the direction of movement has been established it shall not be changed unless the last train has reached the station in advance, and the earlier message is first cancelled under exchange of private number as in sub-rule (11) of the rule 218 below. Thereafter, for running trains in the other direction, a fresh message shall be exchanged in the manner prescribed under sub-rule (2) of the rule 218 above.