G'day Lincoln70,
Hmmm! The entire Melbourne 'suburban' Rail network? Do you have ANY idea of the size of this undertaking? Download and install these two files...
http://www.storage.victrainz.com.au/Jerkers_DEM_maps/Williamstown.cdp
http://www.storage.victrainz.com.au/Jerkers_DEM_maps/HOG_Texture_Set.cdp
...for a 'sample' of the workload that you have ahead of you. Note that the first file is of some 6 MBytes in size. This is a DEM based "barebones" 'route' that covers the inner suburban area of Melbourne. It extends from Richmond (just north of where the image you provide above is located) and extends south to Port Melbourne, including the Webb Dock line and the St. Kilda line (in their original 'heavy rail' configurations). It includes the entire Underground Loop and runs as far as Williamstown (it's namesake), with the 'branch' towards Werribee included as far as Paisley, also including the Altona branch as far as Mobil. It includes the Upfield line as far as Flemington Bridge and the Broadmeadows line as far as Ascot Vale (with the branch to Flemington Racecourse). It extends in the west as far as West Footscray. As you can see, it is but a small section of the total area you wish to cover YET THIS ROUTE IS, AS IT STANDS, 190+ baseboards "large"! Now, you may be intrigued by the term "barebones". This means that the route is no more than the correctly 'shaped' terrain along with certain vector lines painted on as textures (which are provided by the second of the two files above). There are no rails, no road splines, no structures, no 'objects' whatsoever - nada, njet, nichts, niente (did I mention none)!!
You may want to "shift the goalposts" a little! You might also like to avail yourself of the 'camaraderie' that may be obtained from the fellowship of 'like-minded' Victorian Prototype modellers in the Victrainz group, by way of our forum...
http://www.forum.victrainz.com.au
...where you will find much more specific and more dedicated assistance towards your goal (and where you will find that much of what you wish to create is already 'claimed' by others)...
...incidentally, the point work at both Flinders Street and Southern Cross is a mammoth undertaking...
http://www.victorianrailways.net/signaling/completedia/fss57_08.pdf
...(which I am not sure could be accomplished prototypically with Trainz). It could certainly NOT be signalled as per the prototype even if it could be recreated exactly)...
Jerker {
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