I have a map of Adelaide from the late 1920's and I also have one from 1960 just after the tram network was ripped up - Airport Road (and the airport) didn't exist in the twenties but both did exist by 1960.My understanding is that Airport Road was built to provide road and possibly tram access to the airport. Trams would have used the median strip. The decision, in 1953, to do away with the trams put paid to trams going to the airport.Yeah it's lovely and wide isn't it, you'd have to imagine that it was designed with that in mind.
I believe that the tram line down Sir Donald Bradman/Burbridge Road got as far as Marion Road before turning South - that could have been another option had Playford not decided to rip up the whole network.
Airport opened in 1955, trams closed in 1958, you'd have to think it wasn't at least in their mind set or at least planning for future growth and road widening.
Edit: Was Airport road actually built then?
Non-bus transport makes a very minor appearance in the airport master plan, page 18, 10.10.1 saying they have "Adelaide Airport has made provision for increased public transport, by reserving land for a potential high capacity public transport corridor along Sir Richard Williams Avenue."
I read this as to be a tram "of sorts" station and likely ROW provision.
There was planning for right-of-way provision and future extensions of the the Adelaide tram network right up until the decision was made to pull the pin in 1953 - Prospect Road had power provision for trams made all the way up to Marmion Avenue in the north of Kilburn/Blair Athol in anticipation of an extension from (then) Irish Harp Road terminus (now Regency Road) and there was also land bought in anticipation of a new line that was to cut through from Payneham Road to the new growth areas around Tranmere.