Tony P asked:
> Does anybody know when the free vintage tram loop and the free tram zone, respectively, in Melbourne... were introduced?
Assuming you mean the City Circle, that opened in April 1994 and was originally enabled by a new double track in Spring Street between Bourke and Flinders, where no track had ever run before. The media at the time heralded it as the "first new city tram line since 1955" meaning since the Bourke St buses were converted to trams in that year.
Interestingly, the government of the day had promised "free city trams" before the most recent election, meaning all city-centre trams, but claimed on the opening of the City Circle that it only meant that route.
At the time, there were no lines to Docklands, so the western part of the route was along Spencer Street.
From memory, all city area trams became "free" on January 1 2015, leading to massive overcrowding and a huge increase in fare evasion on crowded trams passing beyond the "free fare" boundaries.