For other discussions on the Geelong Line:
Check out these threads:
How Geelong line able to cope becoming a metropolitan line in the future
https://www.railpage.com.au/f-t11386457.htm
Geelong rail expansion and its own metro system
https://www.railpage.com.au/f-t11385957-0-asc-s0.htm
Best case scenario for future of Geelong line (The plan)
I have combined the two concepts on how to still utilise the RRL route and have a better direct route to service those at Geelong and beyond.

This is a good blog post a little outdated (2008) but still relevant today: https://melbpt.wordpress.com/electrification-economics/
Ok here it goes. It is a most expensive proposal ever but I think others alike know this is a long term plan and must get it right for the potential surge of patronage in the South West Region of Victoria and the Western part of Melbourne.
Costs involved are estimates only, may increase as time passes. Gives an idea the scale of such a project. This is probably the best case scenario for the Geelong line. Some needs a detail business case and planning document to see whether such a project could go ahead or if other projects take priority as I focussed on one part of Victoria.
The new Geelong metro line (stops all stations)
- 90 km of electrification on existing Geelong Route via RRL (500 million+ )
- 7 km of Quad between Sunshine and Deerpark + grade separations (600 million)
- Additional 3 stations on RRL (250 million)
- Upgrade track needing repairing (200 million+ )
- Werribee line extension to Wyndham vale (500 million)
- New rolling stock 30-35 trains and stabling facility (1 billion) *
Note: *The existing VLocity trains can be used onto the Warrnambool line, and other lines needing more services. Older rolling stock on other lines can be replaced with these trains. Only older rolling stock will be out of service
Geelong High speed rail (express route, stops at Avalon airport, Werribee and Southern Cross)**
- New double tracks from Geelong to Newport with a divert to Avalon airport
- High speed trains (number of trains to be investigated**)
- New stations at Avalon airport
- Rebuild Werribee station for interchange
- Metro 2 tunnel (four tracks- one set for Werribee, the other set for the High speed trains)
- New stabling yard built
Note; **Planning study needs to investigate costs and benefits of such a project