I’ve been reading a bit on the Mexico City Subway on Wikipedia[link]
Interestingly in addition to station names each station also has a logo assigned to it:
“Each station is identified by a unique logo related to the name of the station or the area around it. This is because at the time of building the first line, the illiteracy rate was extremely high, so people would find it easier to guide themselves with a system based on colors and visual signs.”
Some samples:
