I've rerouted the Lal-Dumathoin line through the unused rail tunnels and station near Old dumathion.
The line now starts at the Main rail hub, goes south then upstairs, passes Old dumathoin, then goes downstairs and crosses the magma bridge which I expanded to 2 wide. From there it continues to lal dumathoin. However the path it currently follows still isn't exactly simple or straight so I may change things before I reinforce. Also due to a lack of powered rail currently the only powered section is the Rail hub- Old dumathoin section which is handy if you need to get to the other side of the city.
Going up those ramps takes a hell of a lot of powered rail. The entrance to the eastern farm is at the turnoff just past the magma bridge, and is powered, but has no rails for about 500 meters.
I'm currently pulling up or rerouting through old rail lines I'm finding littered around teh underground, the ultimate goal is a simple rail network with a line going directly south, north, east and west.
East line is to Titan (complete and powered), South line to Lal DUmathoin Via old Dumathoin (complete but half powered), East Line to Tiliqua's farm (powered but 340 meters short) and North line goes to Mithril mountain. (100 meters short diagonally, unpowered).
So I need approx 540 rails to finish all the lines, 60 power for lal-Dumathoin, 11 powered rails for The Farms, and about 80 power for Mithril mountain.
Edit: we have 52 power rails left and I think about 4 stacks of regular rails, however an hour in mineshafts should get me a few more stacks easily.
Edit: I have about a third of the gold I need for the rails
Edit: Avatar of Armok; I left some supplies in a chest buried in a mountain just past the carrot farm, there is a poppy showing where to dig(dig into the mountain, not straight down)