Niligiri mountain railway is the meter gauge hill-railroad which operates between Ooty at 2200m above mean sea level and Mettupalaiyam at 330m. The steepest gradient on this 46Kms. section, is 1 in 12.3 while the average gradient is 1 in 23. Each passenger coach
is provided with individual brakes operated by guards.In this photograph, YDM-4 locomotive is taking the passenger over a curved bridge, down the gradient. With the steep ruling gradient and curved bridge, the assistant can be literally seen coming out of the cab to check the continuity of the train.