A lot of people have asked why a Z-class tram was chosen for the Queen’s tram ride (rather than Melbourne’s traditional and iconic W-class, for instance).
Here’s the answer:
W and A-class trams don’t have handrails in the middle of the doorways, which can be a big help for older people. B-class trams do, but they may not have wanted to take a high-capacity tram (or two; they had a spare) out of service for this event.
C and D class trams are low-floor, and have few handles — this would have been easier at the Federation Square platform stop, but perhaps not where the Queen alighted near Government House, where there is no platform.
Over time the tram fleet needs to switch to low-floor vehicles, and more tram stops need to be accessible. It does matter for the mobility of those in wheelchairs. As these roll out, they will be able to use more of the tram system.
After all, some parts of Melbourne are most easily reached by tram (including the hospital precinct, which unfortunately and ironically, has no accessible trams serving it at all).
No-step boarding is also faster for able-bodied people, and those using shopping jeeps and prams.
Update Monday morning: There also seems to be some talk that a high-floor tram was requested to ensure more of the crowd could see the Queen at the window as it travelled along.