Just curious: Are there maintenance that can only be done at Epping and not at Newport?I don't know if that's practical or not as I think Epping handles Hurstbridge and Mernda fleets. Perhaps someone with more knowledge can help us out on what takes place where and if another depot can help out for an interim time.
Happy to help on this one.
Maintenance is not the issue, fleet assets that require maintenance can be moved to Newport or Ringwood.
The issue and the reason the line is staying open for as long as possible is stabling capacity and fleet displacement.
Stabling Capacity, Metro simply does not have enough. With the trickle of Xtraps and the 65 HCMTS there is not enough spare capacity to move fleet assets around the network when a line is shut down. This reduces operational fleet capacity, meaning Metro does not have enough trains to run the timetable.
Pakenham East & Newport are being used to overflow displaced units at the moment, but with more HCMTS coming online this is ever reducing. Stabling has come online at Kananook, additional roads are under construction at Calder Park, Victoria Park and Watergardens to help. This is all good and well when you only have occupations on one line allowing you to move assets to keep the timetable running. The sheer number of overlapping projects (MM1, Hurstbridge, Sunbury, Cranbourne Line Upgrades and dozens of LX removals) means multiple stabling yards are impacted at the same time.
For the Preston and Bell removals, 20 roads are isolated from the network. Metro doesn't have anywhere to displace these trains, meaning the Clifton Hill Group is short 20 trains. Spare Comengs can be brought across the network to help, but this eats into 'live spare capacity' meaning trains faults are will result in cancellations as there is no spare capacity. Metro may choose to replace longer sections with busses to reduce runtimes for trains and help boost frequency.
The worst prediction for Metro is during the Frankston Line shutdown scheduled for October - December, where Metro estimates it will be short 33 units during serval days in November due to other occupations occurring on the network.
Similar shortages are predicted when LX removals kick off in Pakenham with 36 roads isolated at Pakenham East.
This is in part why the word 'fast tracked' keeps getting thrown around. Timelines for LX removals are being sped up to reduce occupational overlaps.