<chanting> Do it! Do it! Do it!
It looks good. I will say, what I had in mind was more specifically that the new lines be basically indistinguishable from other subway lines. I think that means lines for the new routes should be shown the full width of existing subways, and each with their own color (maybe like a set of four pastels or something). Maybe at that point the new lines need names, like RR1, RR2, RR3, RR4, or something like that. It would be a way to show that with NSRL (and other improvements) you essentially get four new express subway lines across the region.
Again, the Munich transit diagram is one I had in mind. U-Bahn and S-Bahn have different labels at the end of the lines, but on the map they're interchangeable ways of getting around. It's all one, unified system.
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And obviously, that's just my thinking. You know what you're doing. I'm glad you're taking up the challenge!