Melbourne doesn't really need longer trams, just a lot more of them in
order to provide more services through more capacity. Sydney's decision to
go with longer trams is a result of the perceived constraints on feeding
large numbers of trams through many intersections with lots of
cross-traffic, thus longer trams enabled then to retain the capacity using
far less tramsets. (Terminus arrangements also constrained tram numbers.)
As it turned out, however, they've even managed to bungle feeding longer
trams at less frequent intervals through those intersections.

Tpny P