It does make me wonder if rebuilding the Manangatang - Robinvale line (as SG), a bridge over the Murray, and a new line next to the Sturt Hwy to Balranald would stack up. Especially with the huge mineral sands mines about to start in that area.That would be a hell of a lot of capital investment for running rail to a mine with a 15 year project life and to get the economies working for such an investment you'd have to run the rail right to the minehead which presents a whole pack of difficulties. It's not just land and earthworks that make railway expensive - rail, sleepers and ballast aren't cheap either!
The Sturt Hwy alignment is fairly flat, wide and open - and it's already Crown land.
Having FOUR parallel lines (Yelta, Kulwin, Robinvale, Piangil) across a range of 100km,The Mildura passenger rail study did look at a Swan Hill to Mildura railway line, using a link between Pira (on the Piangil line) & Chillingollah (Robinvale line) and then either Robinvale to Mildura via the Sturt Hwy or Manangatang to Ouyen and thenceforth to Mildura. Both options have similar size passenger catchments (i.e bugger-all) and route lengths, although the Manangatang-Ouyen option would've had less new track and earthworks. In both cases the prospect of having to grade separate at every road crossing strangled the idea.
Thow in the Balrandald line from Echuca(ish) and that is 5 where 3 would likely have done. If Swan Hill and Mildura were connected on one line in the first place (which appears to be somewhat logical) there would have been a lot more traffic potential now.
but alas history...
Perhaps if one of those options was done back in the late 1940s or 1950s when the rail network was being regenerated after WWII - and the prospect of a gauge muddle was barely on the horizon - then it might've been viable as part of a consolidation of the grain branchline network in the Murray Basin.