Okay. I revised the map. This is basically the core of the railway system: the white line, and parts of the red and green lines. I think we should build this first and then we can extend the green line south (underground?), and add the blue/yellow lines later.
Assuming that everyone is okay with this layout, the next step is for everyone to take responsibility for segments. Ideally you should take responsibility for segments which are near your stuff. (For example, I can handle G2-W5.) That's when we can decide what segments should be above or underground, and what the stations should be named.
For where they are above ground we can build below the skyway. The entirety of the White Line should be above ground but there are sections of the Red Line which might work better underground. I don't know, I don't really spend much time out there.
Also, the above ground tracks should be lower than the existing skyway. 10-15 blocks lower. That will make it easier to make it go underground when necessary.