Why not just have wider PSDs to cater for the different door spacings? The difference isn't that great anyway. It's not as though they're going to be opening on the void between the carriages.
I'm actually a fan of PSDs, but I'm unconvinced they can be reasonably implemented on the Sydney network, at least not in a way that doesn't create more safety and capacity issues than it resolves.
The automated system(s) with PSDs that I've used all added 2-5 sec to the dwell as the train slows to sub walking pace, then inches it's way to the correct door location.
The NIFs having all 10m decks means there is a 0.5m to 1.0m variance in the door location between these and the A/B sets - assuming they are built to A/B Set lengths no H Sets lengths.
IIRC there was a bungle in the SPEC of the A/B set's length specification (probably body length vs over coupler length) making an 8 car train 1.0m - 1.5m longer than an equivalent pair of H sets.
All this means the door location will need to vary by about 1m between trains - regardless of how precisely they are parked. (I'm kinda assuming Sector 3 here with an all A/B/NIF fleet).
The other issue is the screens will need to be physically set back from the trains to accommodate the outward opening plug doors, in addition to our already large platform gap thanks to the eclectic - and constantly changing - loading gauge.
IMHO there is great scope for PAX to get caught between the train and the PSDs if it's attempted in Sydney. And when this occurs, no-one will be able to see it.
Someone could be waiting on the platform to board - probably unsuccessfully - at the side of the train door, but fouling the PSD, and potentially be knocked into the gap between the train and platform, especially of the platform is crowded and they literally have nowhere else to go.
In any case, like most proposals, it's worth asking "what problem are we solving here?"
The obvious answer is that the platforms are too crowded.
There are some equally obvious alternate solutions to this issue:
- larger platforms
- better ingress/egress capabilities
- lower (ie less increase in) train loadings
- more frequent services
But when all else fails, just blame the victims/passengers.