The whole purpose of a railway is to reduce the friction of the wheels, to enable a heavier load to be carried for the same amount of power. That lack of friction works against the train if it has a steep slope to climb or descend. The usual way is to tunnel through the hill, avoiding the slope altogether.
This, though, is very expensive, and, when they built the railway westward from Sydney in the 1860s, Engineer-in-Chief John Whitton did not have the money available to him to tunnel through A
