Mexico City metro stations are inordinately large. The corridors seem designed to admit a military procession or a running of the bulls. It often takes five to seven minutes of hard walking to make a simple transfer between lines. Probably to compensate for this, the trains are too small.
The trains run on rubber tires and are very quiet when they pull up to the platform, but are less quiet inside, where the windows are left open due to a lack of air conditioning.