But as far as I understand the question, the problem is a render
in cases of collision. This happens with a small number of stations per
case. So, we don't need absolute importance of stations here, but a
relative ranking of these few stations.
And I suppose, in most of these cases, a non-perfect method like the 2 I
proposed, could work.
The problem is that the renderer would need to do a lot of calculations for
this, which usually is something you want to avoid as that process takes a lot
of time anyway. Walking relations up and down is IMHO one of the last things
you want to do there if you can avoid it.