Sco Mo said the trains could/would use the new metro tunnel! So screwing the capacity of that tunnel.
My route, favoured by a local polli was to run the line due west to the Calder Park raceway then South to Southern Cross.
(this is the massive area of land under the high voltage power lines)
Plenty of space for a station next to Calder Park, providing
1/ Park and ride to those on Calder or heading from the West in the ring road
2/ interchange to regional and urban rail lines
3/ This provides an alternative route and so decentralises transport routes, which is a strategically savvy long term plan.
4/ Potential redevelopment of Calder Park raceway for a F1 venue(currently Victoria paying $50M a year to host F1)
5/ Budget hotel
6/ Train Shuttle from park and ride to terminals reduces traffic congestion around terminals.
The issue is that Melbourne Airport would gag at the potential loss of parking fees, due to a park and ride that is off-airport.