Since we're on the subject here with Metra I have to say I cannot stand the ridiculous nomenclature they have for the system. In an effort to streamline and at the very least appear more comparable to other international systems I've been obsessed over the years with instituting a simple alphabet naming system. The logic they use, or don't use, where a bunch of lines are named after the host freight railroad, or the host freight railroad paired with another direction to distinguish it from another line, in some cases a host freight railroad that longer exists and then some lines are just randomly named like "Heritage Corridor" (I mean WTF?) or based on geography like NCS or SWS. Then you have a line that's named after it's mode of propulsion instead of IC.
It's so horrible.
Imagine the system map here below, in the service order shown and keeping the line color intact, but instead just using an A-K alphabet in round route bullets:
___
Just by delightful happenstance, you have the "Heritage Corridor" (I mean seriously WTF?) given an (H), Rock Island given an (I) (I know I know possibly problematic and wisely avoidable considering I looks like a 1, but it would work fine if a serif letter typeface was used) and Metra Electric a (K)... a (K)!!! How perfect is that? ME branch services could be designated K1, K2, K3 with a smaller number tucked into the circle or just (K) (L) and (M).