We could complete the Airport here for about 2.5 to 3 Billion if we -
refurbed and double track the broad gauge freight from Albion
double tracked and dual gauged the existing standard gauge freight.
re-route the Bendigo line trains through the Airport and Clarkefield.
re-route the Seymour and Shepparton trains through the airport.
Don't electrify and use surplus Sprinters, heavy refurbished for terminating services.
I've come around to Seymour and Shep not needing to go via Airport, instead those people can change at Sunshine. It makes the track work even more simple and cheap if only Bendigo trains go via airport to Clarkfield, and Seymour trains go along the existing Jacana railway.
In my pipe dreams, capacity on the RRL for extra Airport services would be freed up by Geelong to Airport VLine services running via Metro 2, but in the meantime (which will be a while, if not forever) you have to take the paths from Metro 1, RRL track pair is already at capacity, and any excess is better used on Bacchus Marsh or Wyndham Vale locals, especially in peak.
We all have our dreams.
I have gone completely off Bendigo via Airport/Clarkfield.
It means every Bendigo pax from Albion down(including Sunbury), must backtrack to Sunshine to catch their train.
Seymour trains can already go via the Albion/Jacana.
Why they didn't do that when the LXRA are shutting the line is a mystery.
Downside being, not much room on RRL for them to get to Sunshine.
Now for my dream. Been said before.
Send Bendigo trains along the Ballarat, and then across country from Carolyn Springs to Diggers Rest.
Of course in conjuction with Sparks & extra track to Melton.
That would remove the mess RRL left behind at Sunshine, and give all Geelong/Ballarat/Bendigo a clean run.
An expensive new track, but compared to multiple "fixes" needed and now MARL conflicts, probably no worse.