I posted this on the steam forums and the OP has already acknowledged it, however I figured it cant hurt to repost it here.
I did some testing on this and I found a(the?) solution.
Take diagram 5 from the OP, but instead of signals on just 1 side of the track, add signals on BOTH sides of the track for both lines.
That will make the trains go the way you want to.
It was explained somewhere that the signals need to be placed on the RIGHT side of the track for the train to acknowledge it.
At the station you need signals on both sides of the track, because you need a signal for both incoming and outgoing trains, one for each.
If you only have on one side of the track, the incoming train will think that the train in track 1 will continue ahead and will wait for the track to clear, rather than take the free track.