Some finishing details...

[Green_Elite_Cab]

If I'm not mistaken, the operation shown, or another part of it, transported the train and the loco on the barge. That particular branch was a series of track sections connected by lakes (or lakes connected by track sections.

Wayne

Good discussion going on here. Wayne is correct. Keeping the loco off the apron is not a really valid concern. At least in this case. CP transported entire trains up and down the lakes in the Kootenay area using this method from the dawn of steam up until the diesels took over and ran pretty much until the late 80's.

GEC - I understand the concept of the idler cars and of course you are right. I also really appreciate that procedure and the link provided. Thanks!!!

Poor word choice sinks ships!

I did not say the locomotive couldn't go on or cross the apron, only that in some situations it is undesirable for it to do so.

When that GP9 was loading its initial cut of loaded boxcars, it was using idlers for a reason. The barge was otherwise empty, and if you concentrated the weight of the locomotive and those 4 loaded boxcars onto the one side of the barge, that would put it in the position to twist excessively to "port". The barge probably would not tip over, but excessive twisting could very well damage the toggles and other Apron/barge equipment. I've heard first person accounts of horror stories where the toggles or parts of the apron get bent out of shape and jammed together. Its a nightmare to fix and it puts a quick end to operations. True, this might be more of an issue with floating aprons, rather than ones supported by a gantry like the one in the picture and your model, but its still a legitimate concern.

Once those box cars are loaded, the barge is going to to sit lower in the water and become more stable. At that point, a locomotive going onto the other track on the barge probably wouldn't be a big deal. If anything, the barge is going to straighten out a bit. Its only in situations where the weight of the locomotive and cars would be to much (as is the case when initially loading the barge as seen in the first picture).