1. You should be quiet in the subway.

2. You should be quiet in the subway station.

3. You should be quiet on the subway.
4. You should be quiet on the subway train.
5. You should be quite on the train.
6. You should be quiet on the train in the subway station.
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Does #1 mean #2?
Does #3 mean #4 or #5 or #6?

I'd use 2, not 1.

I'd use 3, 5, and maybe 6 (although it's quite wordy!).