What was I thinking when I routed out the inspections pits in the baseboard? I made them just slightly over 4′ wide, which is the correct width. However, I left almost no space for a veneer of any sort. The result was that I was forced into making concrete pits with .010″ thick walls. Following the same logic as with the turntable pit, I suppose concrete is okay.
Because the original excavations were barely wide enough, I had to make the sides from .010″ plastic. There is also a .010″ lip around the top to support the track timbers. This is less robust than I would like; in order to keep the walls straight during installation, I had to brace them out with a rectangle of styrene.
The floor of the pits slopes almost imperceptibly toward the back wall and is cambered in the middle. On the prototype, this would keep all the oil and other drippings toward the walls and allow them to flow down to drain pipes near the back wall. Nobody can tell, even myself, just by looking, but I know this detail is there.
I painted them up with acrylic paints, smearing oily burnt umber, black and raw sienna around liberally, especially under the engine end.