South line: besides the possible junction with the green line in Bryson's SE area, I think the only southerners that would be affected are me and bobsky. I'm not really fond of yellow either, but I don't care which color goes down there.
Only thing is, let's save this line for last / not bother with it for a while (or stop it towards the W end of the Skyranch). The current diagram intersects over Anchorage Island, where I wanted to build a lighthouse. Moving the tracks all the way to the south coast of Anchorage lake seems a bit longwinded, but I don't think I want anything in the air around Furronia either, at least in the south. At worst the line could go down into the moat at the SE corner and come back up in the SW to go on out to the sand mine with a stop at Furronia in between... I'll figure something out for this area.