I made a loop to loop 0 gauge subway by making a subroadbed then assembling the main platform with legs in the pre designated voids of the subway. The subway level is in flat black. It has three subway station platforms and two bridges over a deeper valley:
Floating subroadbed clamped in placeChecking for clearances
Temporary piers in place
Trestle piers to finish valley. Note exposed subway in background.
Track forward of station platform
Track behind platform and in front of platform along with siding nearest fascia.