I don't think you are familiar with the nature of rail operations in the UK (and a large part of Europe). Peak hour services on commuter lines here are running at headways around 3 minutes (i.e 20 trains
As for your second point...
no i am not famiiar with uk, but i live on the main line of 100 miles , everey day there a train comming nto my town at 25 min apart,, and it is a singal main line,,,,
It would be perfectly possible to set up an interface in Trainz to control the points (switches), which then in turn control the signals in an acceptable way, as now. In a way this has already been done by some of the path/route setting rules. What is lacking are better interfaces for building the rules and using them.
why don't we keep it simple,,, i run a dual main line in trainz andi have about 15 to 25 trainz running at one time with no problems,,, it woud be great to run real time with trainz, but to do that you would need more ram bigger processor and i dont think nv3 will let any one have acess to the code of trainz,,,,,
I have a garden railway which is controlled from a ten year old laptop (running Windows Me) - the display looks like the panel diagram you would see in a modern(ish) signalbox and routes are set by clicking on either pre defined paths or individual points (switches). So I don't think state of the art hardware is required for the task.
oo man, i wish i had that kinda of $$ to do that in my back yard,,, eee the wife would kill me,,,,,,