types
  normal rail            (tracktype and vehicletype)
  elrail                 (tracktype and vehicletype)
  3rdrail                (tracktype and vehicletype)
  elrail OR 3rdrail      (only vehicletype)
  elrail AND 3rdrail     (only tracktype)

compatible:
  all are compatible to each other

poweredness:
                                    elrail
  rail   ->  elrail OR 3rdrail  ->           -> elrail AND 3rdrail
                                    3rdrail