no joke and I should have said for people taking Prams, trolleys and disabled persons. already v sets run off the edge of platforms in many places in the mountains. also the blue mountains don't need high patronage double decks if you can put 8 single decks.
I catch it regularly, and at different times of the day. Generally there plenty of seats down to Springwood, after that it gets crowded and only standing room from Emu Plains, especially during peaks.
Which means, a AGV style train could do all west of Springwood with only a couple limited stops east of Springwood. (Penrith, Parramatta, Strathfield...) All station service east of Springwood could be then just serviced with wide gauge sets.