Some terrain adjustments, most notably in the lower left corner. Most of the layout is at 0" elevation and the O-gauge Fastrack is level at 0". The elevated San Sebastian narrow-gauge RR is at 7", and the tunnels over the narrow gauge at 13", rising to a peak above that measure.
There are no grades, though small grades could be added, perhaps the yard could dip down gradually, and Dagny Siding and the Lift-out Reardon Bridge could be on a slight up-grade. The elevated terrain drops down from 7" to 0" steeply in many areas, which might be opportunities for rock walls (which are hard to show in an "birds-eye" view).
The goal of this design is to create multiple routes for train-running, and it does that. It doesn't have much for industry switching, but it does have the three-track Taggart Yard. Two design principles that could not be followed are 1) having a yard lead to switch without fouling the main, and 2) easements: there are some, and the O-60 turnouts are like easements compared to the layout minimum of O-48, but otherwise there just isn't room to do much more (like easements going into all of the O-48 curves). Giving up more easements is not really a deficiency, as the O-48 is already better than O-42, O-36 and equipment for O-27. The O-60 routes and variations are already wider than the next standard of O-54. And there are even some O-72 and O-96 curves. There are always trade-offs 
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