That's exactly what I've been wondering - chicken or egg stuff.
PRM approaches need a minimum distance of 1035 metres between rwy centre-lines. Where did they get that number from? PRM approaches (and equipment) have been in action since the mid/late 90's, I think. But SYD's 3rd runway was around before then. So did they look at where PRMs where going to be conducted (eg, SYD) and write the minimum requirements accordingly? And develop equipment specifications accordingly?
OR - was SYD's 3rd rwy built where it is because 1035m was known to be the minimum for this new-fangled, up-and-coming PRM stuff? And the rwy not built out any further in order to minimise the noise problems? But I wouldn't have thought PRM was on the drawing board at the time?
No issues with it all, just interested in a bit of the history.