With the number of stalls being 4, supposing they had all 5 engines, where would the 5th one be?
Indeed! Maybe double-stacked with another engine?
Anyway, for the turning radius I made a pretty simple assumption.
Since there are 4 wheels on each rail, when going around a curve, each wheel can be approximated as a point on a curve. Connecting these points describes an arc, which we can then get its radius.
There is “play” with these points also because the wheels have thickness to them. (Technically, the driver wheels cannot deflect because they are rigid in the frames). In the above picture, I deflected the pilot truck until the rear wheel is near but not in contact with the inner crosshead guide. Then I draw an arc connecting the 4 wheels together.
This process gives an arc of about 1350″, or 112′, which is less than my assumed smallest curve of 139′, and certainly much less than 278′ on the mainline.
So indeed, there’s plenty of room for the pilot truck to turn. Generally, rail curves are made to be as large as possible, so in reality the pilot truck does not swing that much.