I managed to put in a few hours in the basement this weekend, with most of the time taken up with marking and drilling screw holes for the various framing components. Let's go to the graphic:
The plywood/1x3 base for the Transition section (C) is complete, although not as precisely constructed as intended. My hope is that I can smooth out any discrepancies affecting the track by adjustments to the foam layers. I also completed the L-girder and crosspiece frame for the Rural section (D) and it turned out very well. I also prepared the frame for the West Yard section (A) but I need to mark the location of the 2x4 wall studs first, as those will determine the placement of the crosspieces. (Ladies, chime in here with the usual "stud finder" jokes.)
I discovered a complication earlier in the week in that the tape measure I was using for the initial measurements of lumber had a loose clip on the end which, when stretching the tape, caused an extra 1/16" to show up. So, for example, when cutting an eight-foot 1x2 into two four-foot sections, I ended up with a 48 1/16" piece and a 47 15/16" piece. To be safe I had to re-measure everything not already constructed and I hope the already-built sections will not give me too much trouble. Fortunately I tend to work with more than a 1/16" margin of error so I think I'll be all right.
I am currently in negotiations with our budget director about the diversion of some of our tax refund to address transportation infrastructure needs. Stay tuned for an update on that!