Michael pretty well summed up my thoughts in his previous posts. The Garratt design really was ideally suited for lines with light rail and light bridges, much more than the US main lines with their heavy rail and heavy bridge loadings, combined with very generous clearances compared to the rest of the world. The Garratt design would have been well suited for many north American narrow gauges, but they were largely not needing new motive power. Or were using the used locomotive market to meet their needs. Or, like the D&RGW, were relying on keeping expenditures to a minimum.
The coal and water capacities of the big standard gauge tenders exceeded anything the Garratt had. As I said, to attain something even close would have required bunkers that would have reduced vision for the engine crew, not to mention the probable need of an auxiliary water car. The Garratt was well suited for some kinds of service. The big articulateds used in North America met the needs here. The N&W A, the UP 4000, or the DM&IR Yellowstone were well suited for their work moving heavy trains over long distances with the fewest intermediate few and water stops. Different needs resulted in different locomotive designs.
Having thought more, I think the C&S and RGS lines were perhaps two of the best possible locations to really use the Garratt's qualities of flexibility, tractive effort, and ease on track and bridges. But both had management that was trying to abolish them, and wanted to keep costs of improvements to a minimum. Still, it is interesting to think what a 2-8-2 + 2-8-2 might have accomplished with the Leadville to Denver freight business, or stock trains on the RGS.
Thanks, CJ, for opening an interesting subject.
