The Melbourne Metro is just a new tunnel on existing lines, so I would guess they are going to have to support some kind of interoperation between CBTC and non-CBTC? I mean, the ability to run CBTC trains on non-CBTC track or vice versa?
This is different from Sydney, where the Metro lines are physically disconnected from the traditional rail lines. (Apparently there is still some track linking the Northwest metro line to the Main Northern line underneath Epping station, legacy of the old Epping-Chatswood Rail Link, but it is blocked with off with stops; there is no plan for any rail connection between the new Metro West line and the traditional rail network, despite the fact that remnants of the old Carlingford line are directly adjacent to the site of the new Metro West maintenance facility, meaning they could create such a connection if they wanted to.)
This is different from Sydney, where the Metro lines are physically disconnected from the traditional rail lines. (Apparently there is still some track linking the Northwest metro line to the Main Northern line underneath Epping station, legacy of the old Epping-Chatswood Rail Link, but it is blocked with off with stops; there is no plan for any rail connection between the new Metro West line and the traditional rail network, despite the fact that remnants of the old Carlingford line are directly adjacent to the site of the new Metro West maintenance facility, meaning they could create such a connection if they wanted to.)