Being at the terminal of a transportation system (such as the subway) often indicates choices. Places of commotion and confusion often appear in dreams when choices are being confronted in life. Many times, the dream experience is a good place to test various choices with a more open mind than the waking world permits.
The initial question to ask about the subway station is: Do you have the means to ride any train, only some of the trains, or none of the trains?
Who is with you in the subway? Are they deciding which train to ride or are you leading them through the station?