Dhn route was the last of 3 lines. However it grew at a rampant rate. The difficult terrains were there but still passage was made and trains runs with good speed.
Moreover GC was electrified much more before main line and elocos served the purpose.
The youngest member (3 routes) but by far the best. ( sorry if I hurt the sentiments of anyone). Moreover dhn controlling and mgmt of train is far much more better