Ah ffs… what is it with this forum and not allowing edits after a few minutes.
You’re right – I’m too sleepy to make a proper argument. I managed to cause gridlock finally with several million worth in trains on my network. The loops need to lose the “entry” signal at both ends, or trains will make a stop right in the middle of the trackchange section (The V shape where the rail splits in two)
Think I managed to show the issue using the original diagram – All of the signals will make a train drive right up to it and make a halt until the way is clear. This causes a gridlock with enough trains using four signals. The solution to that is to simply get rid of the entry signals so the trains only make a stop “inside” of the loop, leaving the exits clear at either side.