Opposite to the Normal DirectionOn a line for which the signalling is provided for one direction only, Normal applies to the signalled direction. On a Bi-Directional Line, Normal applies to th... More of rail traffic on a particular line. Also
known as Contra-Flow when applied to a Bi-Directional LineA line on which the signalling permits trains to be signalled normally in either direction. See Bi-Directional Signalling More.