Ok having read all the recent posts, it’s clear that people are misinterpreting what I posted.
The key thing to understand here is that no train should be permitted to enter the single line section unless there is a clear protected slot for it to wait in and therefore entry to the single line section should be controlled. If you experience gridlock, then your line is over-capacity and it requires expansion (as I explained in my guide under “Important thing to note here…”).
So in the examples provided by Tossi, in that four trains are being used on a line clearly only designed for two trains, what you’re proposing in your diagram is pushing the line over capacity and hence will fail. The solution in this case would be to expand the controlling sections to allow the protection of four trains – so to be as clear as I can be: four trains === two passing loops.
Remember that the aim of allowing trains to pass each other on only one track is a process of reducing construction and running costs to an absolute minimum while maximising on returning revenue. Should you reach a point where it is no longer viable to have trains pass each other then, as I mentioned in my guide, you should consider upgrading the route to two tracks.
I hope this clarifies things, if my guide wasn’t clear enough to start with.
While posting, please bear in mind that some people might not instantly get what you’re saying, have a little patience – there’s absolutely no need for hostility.