On the line from Mandalay to Lashio, Burma Railways not only had curve radii starting at 330 ft (100 m), but also a long gradient of four percent. For this purpose, four class GA.I Garratts were built in 1924 as Double Consolidation, i.e. with the wheel arrangement 2-8-0+0-8-2. At the time they were put into service, they were probably the most powerful meter-gauge locomotives in the world.

Due to the narrow curve radii, the innermost driving axle had a lateral displacement of 3/8 inches (9.5 mm) in both directions. On the four percent steep gradient, the GA.Is were able to reach 9 mph or 14.5 km/h with a 200-ton train.

In 1927, a single compound locomotive was ordered for comparison and was designated GA.II. This also only had two cylinders at each end, with the high-pressure cylinders located behind the cab and the low-pressure cylinders in front of the smoke box. Since the additional complexity apparently didn't pay off, the other locomotives were built with simple expansion.

Standard variant with four equal cylinders

flickr/Historical Railway Images

Three GA.IIIs followed in 1927, which were largely similar to the GA.I, but had the smaller superheater of the GA.II. In 1929 Krupp delivered eight GA.IVs, which were similar to the previous locomotives but again had a larger superheater. According to A.E. Durrant, all four classes were retired due to damage during World War II.