Metro assigns all the rail lines colors, but also defines the Rapid (7xx) lines as Black, which we don't yet use.
I've found a use case where you're waiting at a busy stop, and you can take either the normal local bus or wait for the Rapid bus, and so you keep both trips up.
You then want to be able to quickly distinguish between the two.
That would be a reason to use the black Rapid bar.
Otherwise you have to read the destination texts, which is annoying. Especially if you're transferring off a series of trains, where you knew everything you needed based off colors alone.
We had user-request for rail colors
Metro assigns all the rail lines colors, but also defines the Rapid (7xx) lines as Black, which we don't yet use.
I've found a use case where you're waiting at a busy stop, and you can take either the normal local bus or wait for the Rapid bus, and so you keep both trips up.
You then want to be able to quickly distinguish between the two.
That would be a reason to use the black Rapid bar.
Otherwise you have to read the destination texts, which is annoying. Especially if you're transferring off a series of trains, where you knew everything you needed based off colors alone.