Interpretations...

Music | Breathe Me by Sia Furler

Last evening, I was dreaming I was on a train underground, maybe the subway...

Subway
To dream that you are in the subway, denotes that you are reaching your goal via unconscious methods. You may be exploring hidden aspects of yourself. Alternatively, it suggests that you are making a hasty decision.

Train
To dream that you are on a train, is symbolic of your life's journey and suggests that you are on the right track in life and headed for the right direction. Alternatively, you have a tendency to worry needlessly over a situation that will prove to work out in the end..

Interesting the way the Subway is described. I worked pretty hard in 2006, more so on creativity and trying to reach, or at least affect my subconscious. I'm not sure what my exploration has brought, but I do think I was affected. As far as making any hasty decisions, I think waiting decades to move forth is long enough.

As for the Train interpretation, I may be on the right track, but it seems I haven't been moving in the right direction!