Bouncing ideas around for a small/micro urban layout.

[Mudkip Orange]

If you wanted to start *really* small, you could do a T-track module where the tracks pass under a Taxiway. There are many examples... Minneapolis's LRT ducks under Runway 12L/30R, the Chicago Blue Line ducks under ORD taxiways A and B, Dallas Orange Line crosses DFW taxiways Y and Z.

 

You could also model a train that loops around serving several terminals, as in the case of the JFK Airtrain or the PHL Airport Line (e.g. the artist formerly known as R1). The latter is interesting in that it's a fully FRA-compliant commuter route, so trains can (in theory) inter-operate from any of the other lines into PHL.