Here's my treatment of a track which had to go directly through a wall to get to a staging area. I built a huge wood warehouse flat (40" long by 12" tall) of my own design, and it has become another location to spot cars during operations. Three 40 ft freight cars can be spotted along this loading dock.
Now the hole couldn't be just a hole...it had to blend effectively into the scenery. I built a girder bridge sized to pass through the hole, and laid track typical of tight industrial territory. I spent some time making sure of my measurements before even cutting the hole...and also the track had to be able to handle a small locomotive and 40' cars without any interference. To the right of the area pictured is a switching yard which will ultimately feed a carfloat. To the left of the tight curve it feeds a staging track. Hopefully that explanation plus the photos make this project understandable as well as enjoyable. More weathering and a bit more detailing are planned for the warehouse. Photos aren't the best but I'm not a photographer...just a modeler...
Bob
