Geelong via Metro 2 would be far quicker and more efficient than unnecessarily going via Sunshine. Other than shared tracks with the Werribee line through the Metro 2, it could easily have its own express tracks from Newport to Werribee. I think that it is stupid that we are putting so much strain on the Sunshine-City corridor, where there is a viable alternative for the Geelong line. Geelong, Wyndham Vale, Melton, Ballarat, Bendigo, Sunbury and Airport trains will hardly fit into 3 track pairs, especially if you add Seymour line trains to the mix. Take the Geelong line out of the equation and you have the opportunity to provide more services for Regional Victoria and provide a separated Seymour line and potentially Bendigo line.
Under this proposal, the only shared tracks that V/line would have with metro trains would be Geelong trains through Metro 2, and Bendigo/Seymour/Ballarat trains through the airport line tunnel to Sunshine.
Let's crunch the numbers once again.
Geelong via MM2 would not be quicker and would triple the cost of what is on the table now, RRL was designed to have 2 track pairs. The Werribee line was not. Above ground you are talking about a complete rebuild of every station, overpass, underpass, bridge and property acquisition. Tunnel, just forget it. A track pair with 6 - 10 TPH does not outweigh the Billion dollar costs of redesigning the western suburbs. Even more so you have High Speed from Geelong that will get stuck behind SAS Metro Services in MM2.
This is the same problem they had with MARL all the money it would take to have a bloody airport train every ten minutes. But the cleaver little bean counters figured out they could justify the cost if they had 30TPH over the 6TPH. HCS allows for a theoretical of 32/34 TPH. Operational around 24 - 32TPH. So some more numbers.
The MARL tunnel will have the same capacity as MM1 30TPH (trains every 2 minuets)
-Sunbury & Melton via MM1 trains every 4 minutes to each line. (30TPH)
-Bendigo is still running via Sunbury at this stage. But that could change deepening on what the MARL biz case looks like. That eats the last remaining paths on the Sunbury line. 20 minute service (3TPH)
RRL (Sunshine to SCS)
-Wyndham Vale services all to Sunshine every 5 minutes (12TPH) leaves room for Melton services if need be.
-Geelong every 10 minutes (6TPH)
-Ballarat every 10 minutes (6TPH)
-Airport every 10 minutes (6TPH)
Thats 18 TPH, less than the city loop currently handles.
If Bendigo and Seymour are included 20 minute service each, a further 6TPH
24TPH which is doable with conventional line side signalling, we haven't even got into HCS territory yet.
You could very easily run trains at 160km/h in MARL it will be all of a few minutes from Sunshine to SCS.
Under any proposal there will be no track sharing, those days are well and truly over. Independent and segregated lines. I can see the pitch folks now once we start hearing of Vline train faults in MM2 delaying hundreds of thousands of Metro commuters. It is the basic premise of Metro Lines. Faults on one line do not cascade to other parts of the network. That is why the Government spent 3 Billion on RRL, it is why the government is spending 11 Billion on MM1, it is why plans to segregate RRL are underway and it is why MARL will further segregate lines. The days of one train taking you were you want to go are over. Melbournians will need to get use to changing trains to complete their journey just as those in other major cities do.