Commins Coch, train heading towards Machynlleth after coming down the bank from Talerddig.
Commins Coch Halt was on the western side near the foot of Talerddig summit, and 75004 is dropping down the 1 in 113 grade, heading down to Machynlleth.
Talerddig summit is about 700 feet above sea level, its 120 ft deep cutting being the deepest railway cutting known at the time it was excavated.
75004's steepest climb would have been at Pontdolgoch, a short 1 in 71 grade, whilst services running eastwards in the other direction away from the coast face the steepest section with its 1 in 52 three mile climb between Llanbrynmair and the summit