The most unique in NMR.... As the loco is always connected at the Mettupalayam end of the train, loco pilot can not see the track ahead. On the edge of each carriages stand the signal guards. Practically only the guard in the front can see the track ahead, as the route is riddled with 200 plus curves. The first guard passes the signal to the second, and then to the third and so on. Finally the loco pilot gets the cue who drives loco without really seeing the track ahead. It has been going on like this for more than a hundred years now.