I would love to see Metro 2 quadruplicated between Newport and Southern Cross to take Geelong line trains back onto the quicker route and allow for more local use of Wyndham Vale and Tarneit. But that is a tad off topic.
Here's my realistic scope, after duplication to Melton:
- Electrify to Melton
- Quadruplicate between Caroline Springs and Sunshine, Melton and Wyndham Vale local services stop at existing stations, until RRL beyond Sunshine, where Melton joins Sunbury line.
- Passing loops at stations for V/Lines down from Caroline Springs.
- Planning for Bacchus Marsh electrification, and Wyndham Vale/Werribee quadruplication/eletrification.
- A few level crossing removals where required.
- 130-160kph track speed for V/Line loops where possible.
Opened with Melbourne Metro in 2026, this would be relatively cheap, I'd assume. Construction would probably start in 2023/24, by which time Bacchus Marsh, or even Ballarat might be viable considering the growth and demand in the area.