You may not notice today’s faux pas until it is obnoxiously violated by chattering long-lost friends or by the family of tourists who also happen to be morning people. The unwritten rule? Do not talk during rush hour. Now, while this holds true for both morning and evening rush hours, the regulars tend to be more tolerant during the evening rush hour since they’re not still waking up. Still, they are probably recovering from a painful day at work so the more you can tone down your evening chatter the better chance you have of getting home without someone tripping you on your way off the train.
In the morning, however, it is absolutely imperative that you do not talk. If you walk on to the train and see a friend you thought had disappeared from the face of the earth, it is perfectly acceptable to say hello and save the actual conversation for later. If they’re a regular, they will understand that you’re not snubbing them, you’re just being polite to your fellow morning commuters. On the other hand if they do think you’re being rude to them, maybe they’re not a friend you want to reconnect with anyway.
If you absolutely must talk during rush hour, then please keep your conversation to yourself. No one else needs to know your work schedule or what you're making for dinner or how you're going to break up with your boyfriend tonight.