the two trains seem to represent two factions of human society.
the faster, more modern train has those who've learned their life lessons
and are ready to 'advance' into another phase of earthly existence. the
slower train contains souls which are needing extra time to feel that
they've completed their course.
you'd had a wider perspective view of the situation, so you're probably
intimately aware of the situation, as if you were involved in the planning
of how to deal with the split. the half-house is showing how this apparent
separation of some souls from the collective whole hasn't harmed anything.
the blue tourmaline appears to be a 'personal reward' for you, after the
separation. it could be that this indicates your role as a guide for those
who'd been on that dirt encrusted train. [it is said that: blue tourmaline has the
ability to accelerate the development of psychic mediumship and channeling.]