Originally Posted by orulz
I for one like "named" lines, like London or Tokyo. It sort of gives each line a personality. Maybe it's not as efficient as colors in some way, but then once you have about ten lines you reach a point where you run out of easily distinguishable colors to use.
CTA with its eiht lines is pretty close to reaching that point. So what's left? Black/White are probably off limits because of racial undertones. Of course, there's gray. What else? Aqua? That makes ten. Any others? Lime, Indigo? To me it seems like those would be too hard to tell apart from other colors already in use.
Yellow. The Skokie Swift is such a short little dink of a line that it probably doesn't merit a full color like the rest. Minor platform extensions and a rebuilding of Dempster would allow alternate Red Line trains to continue beyond Howard, and Yellow could be re-assigned. (Of course, Skokie might protest at a one-seat ride to Englewood)
It would also make Howard a lot simpler to operate, with Red Line trains always on the center tracks, Purple Line trains always on the outer tracks, and no Yellow Line to muck everything up.
After that, there's (according to Mr. D) aqua, lime, maroon, and magenta. If proper care was taken, the Maroon Line would not cross the Red Line, the Lime Line would not cross the Green Line, etc. At a very minimum, they could never interline on the same tracks.