Tony, 
The free tram in Adelaide was the direct successor to a free bus over an almost identical route. It started in 2007 when the tram was extended from Victoria Square. 
The free 99B "Beeline" bus was started in 1973, I think. (I have some original brochures stored away interstate, so take that as reliably as a 40 year old memory might be).
Mark

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-------- Original message --------
From: "prescottt@ymail.com [TramsDownUnder]" TramsDownUnder@...>
Date: 11/11/2017 15:39 (GMT+09:30)
To:TramsDownUnder@...
Subject: [TramsDownUnder] Free tram sectors in inner Adelaide and Melbourne

Does anybody know when the free vintage tram loop and the free tram zone, respectively, in Melbourne and the free sector of the Adelaide tram were introoduced and by which government in each case? (I can work out the government if necessary if a get a date for each.)
As a non-kosher rider to the Adelaide question, does anybody know when the two free Adelaide bus loop services were introduced? TIA.
Tony P