As the question says, an impossible (not earth) futuristic world has a subway system spanning across the entire planet and I would like to design its transit map. The obvious problem with doing this is the scale, as it would be way to large to draw by hand.
Just to be clear, I only want to design the transit map, not the actual metro system. You can assume a city-wide planet so population density and above ground stuff don't impact the map. In fact, it should look just like your everyday transit map but on a massive scale. Which I know wouldn't be useful, but I'm not going for realism here.
Unlike conventional maps, transit maps are usually not geographically accurate—instead they use straight lines and fixed angles, and often illustrate a fixed distance between stations, compressing those in the outer area of the system and expanding those close to the center.
The world's subway system is not defined, meaning there is nothing to base the schematic diagram on except the world's dimension. My planet is about the same as the earth, considering there might be a station every 1km that would make for a grid with a width of 40,075!
So, do you have any idea how to draw a giant transit map?
So far, the research
Nathan Hellinga's Processing.py subway map generator resembles what I'm looking for and looks great ( but the algorithm wouldn't scale well to a very large grid.
Jannis Redmann's generating transit map theory bases itself on real world data. Maybe it could be used with generated data, but then the question remains on how to generate that data.
My idea, a random walker
Basically, roll some dice and based on a predefined set of rules: go forward, place a station, turn... and repeat countless times until the map is filled.
*just to be clear, I'm looking to design a single giant transit map, preferably using some algorithm, and then tweak it manually to fit my world better.