ok I'm sorry if i came over a bit strong i just think that my system would be more inline with Ishka than the current one.
here is my system (it may need some adjustments)
tiers:
Colossal
Huge
Large
Normal
Small
Tiny

lets use an example to start. say person1 wanted to go from a Small station in the necropolis to another Small station in The Academy, with the current system person1 has to know exactly which terminal to take him to the next stop on it's route then figure out which terminal that's in. the route might take 1/2 hour or 1/2 day to get there depending on how many mistakes made and number of stops. my way person1 only has to know to go 'larger' (Large-Huge-Colossal) and then 4-6 station names to got to the right Colossal then the right Huge etc. plus the map system for this would be easier to use, thus decreasing time spent traveling. simply input station name and sometimes size and it will show you the route required to get there, it would be easier to remember then a convoluted map full of black lines and blue lines. simply 4-6 station names and your off.
on another note: accidents are going to eventually happen, stations shutting down, terminals not working, riots, etc. if you can't go too these places in the current system, entire lines shut down which can cause more lines to shut down or may be overloaded by passengers trying to get to and from work/home/shops etc, while my system is designed to compensate for redundancies. i think that it is because of these features that makes other districts more available to PCs and NPCs while the current system seems to stifle it. the reasons outlined above convince me that my system is better and should replace the current one.

PS. I'm sorry if i take away peoples fun of making things. i am only trying to contribute and point out flaws that could be fixed, which makes a more fluid and enjoyable setting for the DM and players which I'm sure most if not all of you are.