Decoding some mysterious signal diagram icons

[Lacathedrale]

I've never had a joint operating session, let alone exhibited  - but i am struck by how that could be a really interesting operational paradigm. Two signallers shuttling trains back and forth (maybe some kind of random chance of another train being dispatched before the previous has left, etc) and a third operating the pickup goods turnaround.

 

I think we may have wrung the discussion fairly thoroughly on this - thank you all!