there are a couple of repeating objects at stations. For example at german stations in the space between tracks there were often regularly spaced pipes, where hoses could be connected. In Japan i've seen structures similar to small step ladders. I've seen old stations that had planked walkways for workers between the tracks.
Such things might help to fill up the space between tracks, which being green looks a bit strange. This is much more visible for pak128 than for pak128.britain. Reason for this is, i think, the much duller ground of the latter.
To fill the gap up with ballast, might cause some ugly colour differences? Perhaps this could be ameliorated by newer stations having lighter ballast, so it fits several tracks from the same aera only?