The key words in the Media Release are ".............. spend up to
$ 220m converting the Mildura line to sg ". Only $ 41m has actually been allocated
to upgrade Murtoa - Hopetoun (sg) and Maryborough - Mildura (bg) to 21 tonne axle loads . In reality this probably means a heavy tie renewal cycle, a top up of ballast and some re-surfacing .
A demonstrated business case would have to show the financial benefits of gauge conversion were worth the extra costs involved. If the traffics offering ex Mildura primarily need to get to Melbourne and Geelong then they can do that now on bg and gauge conversion would seem hard to justify . If volumes need to get Interstate then standard gauge is the logical option, as access is then available to NSW & SA as well as Melbourne, Geelong and Portland .
We shall see .
Given the Hopetoun line is already sg and can access Geelong, Portland and Melbourne via Ararat that would make sense to upgrade that route and provide a cross country link at some point across to the existing Mildura line as sg and then gauge convert that point North through to Mildura.
South of that point including the other two branch lines radiating from Dunolly can stay as bg lines and still access Geelong, and Melbourne via Ballarat and/or North Geelong as now .
The immediate track upgrade on the Hopetoun line can safely use sg concrete sleepers. Between Maryborough and Mildura it would be smart to use dg concrete sleepers . IIRC all track renewals through all lx between North Geelong and Mildura have been done as dg for some years now . (Maryborough - Dunolly is dg, but the sg is basically not used these days. And Maryborough - Ararat is sg but currently not used.)
Wooden sleepers have become very difficult to source good quality these days . The new generation slimline concrete sleepers have proven to be very cost effective especially since they can be mixed in with wood over several tie cycles till the whole track eventually becomes concrete .
V/Line is just starting to see the reduced maintenance cost benefits of concrete sleepers as the remaining wooden sleeper sections of Class-2 track are being replaced by concrete in the Geelong, Ballarat, Bendigo & Traralgon corridors . (The concrete sleepers have a much longer life, and with light DMU axle loads the tracks require less maintenance than with wood.)