There are always grey areas which have never been clearly defined. For
example, there is an ongoing argument between the RTA and PTC over who is
responsible for level crossings on the Deniliquin and Moulamein lines.
As to drivers, there would be an endless stream of red tape if the DOT
wanted to certify every releiving V/Line driver who had to work beyond
Echuca, or every single piece of PTC rollingstock which could ever
conceivably run on those lines. As those lines are not connected to the
SRA network, I would assume the DOT leaves everything up to the PTC.
The DOT once tried to tell SLSPG that they couldn't run to Albury or
beyond Echuca as J515 and the heritage cars weren't certified by them to
run in NSW. I think 707 Operations also had a Deniliquin trip cut back to
Echuca for the same reason. AFAIK, there is no bg rollingstock "certified"
by the DOT to run on bg lines in NSW.
For through working of sg rollingstock, that's a different story. I think
you'll find all standard gauge PTC rollingstock can work as far as Albury,
most Freightrail stock meeting the size/weight requirements can work to
Wodonga Coal Sidings and Bandiana.
Cheers
David