I began playing with this design over the weekend, and thought you might enjoy looking it over. The outside mainline is O72 minimum, the inside main is O60 minimum (O54). The grade at the top of the plan transitions to Atlas-O at O54, with one curved O72/O54 turnout on the elevated trestle over the yard. Room for a turntable! Not much industry spurs yet (no buildings and etc). There are two return loops - one elevated and the other around the turntable/yard.
A work in progress. 2.5% grade (maybe 2.6% - see what the final design has), moderate, with a grade inside the tunnel on the left on the outside main. 6" elevation where the lines cross on the right, and the loop on the left is at 9". O72 turnouts, except in the yard (O60) and the elevated O72/O54 Atlas.
The design uses one of the compact double cross-overs that I have been posting under different threads, I was curious to see what could be made of the idea. The center-rail spacing on the double-track mains is 5.25", halfway between the 4.5" of Atlas-O, and the 6" of FasTrack (too wide for my eyes).