rail map generator: half-loop lines and self-intersecting lines

[SlinkierApple13]

How to handle these two types of lines neatly in the rail map generator?

1. Half-loop lines: a line that contains a loop, but not a loop line. Example: Piccadilly and Central Lines of the London Underground.
2. Self-intersecting lines: a line that interchanges with itself. Example: Circle Line of the London Underground.

[Swiftiecott]

It seems that impossible to make these two types of lines in RMG.

Since the real-world railway systems of Hong Kong MTR, Guangzhou Metro, Shanghai Metro, and Shanghai Suburban Railway Airport Link Line, which are used for references of RMG's four info panel styles, does not have any lines be half-loop or self-intersectng.