This appears to be quite an old document (2012 judging by some of the dates in the screenshots, and the network map) but fascinating nonetheless, thanks for posting!

I'd be interested in learning how the signalling tech has evolved over the years. There has always been a push by PTV (the government body responsible for public transport in Victoria) to establish a "turn up and go" timetable where trains depart often enough that you shouldn't need to plan ahead. One of the restrictions of the old signalling system was a fairly large minimum distance between trains that prevented frequent service. This caused some congestion, especially in the hub and spoke model of the Melbourne network where many lines converge to share tracks as they approach the CBD.