As with the Canyon Module, I'm using Woodland Scenics N-scale foam roadbed. Here you can see some fairly large pieces of that material installed, these areas being where a large section of yard sidings are planned. Although I did some visualizing with sectional track seen here, the final track installed will be flex and specifically placed to maximize the curve radii.
The 2' piece of foam riser seen in the photo is not really going to be used on the layout but I did use it for identifying some of the track lines. You can see a faint curved line drawn on the lower left side of this view, this line is for the outer mainline on the lower right portion of the layout plan. I often use the foam risers as a flexible sighting tool, in this case I pinned it down along the straight edge (at the left) entering the curve and similarly pinning it down at the opposite end coming out of the curve, adjusting the placement of the material at this end as needed to get a smooth curve naturally resulting from the springy characteristic of these risers.
The other end of the module is seen here. The roadbed at the right is the outside mainline transitioning out into the covered portion of the track plan. The "S" curve of this line was established using my springy riser technique, the result being a very gentle set of curves with some easements separated by roughly 6" of straight between them.
One of the reasons I was playing with the track spacing (between the inner mainline and the yard baseline track) was to establish as large a radius for the loop-back curve in the yard. The position of the turnout at the entry to that curve being moved slightly right added an estimated 1/2" to the radius such that it ended up roughly equal to the standard sectional 195mm radius.
This view provides a bit more perspective on the developing module. You can see the legs attached on this end with recessed bolts (so that this module will attach properly to the next module). The legs are a bit unstable as they are seen here, I'll be adding some cross-bases a bit later on to correct for this and added stability will come with the module attached to the rest of the layout.
No side panels installed yet but I expect to add these relatively soon. This is because the side panel on the right side of the module makes up a critical part of the structure which will hide the outer mainline as it runs around the outside of the service and freight yards. The board seen rising up from the module surface is the back wall of the hidden section and provides much of the strength that will be needed for the "armrest" for the yardmasters as they work setting up the freight consists.