This is the second (and only one remaining) in what was a series of
two caches called the "Greater Melbourne Traffic Islands" (GMTI)
series, placed on those "wasted" plots of land around which
vehicles travel; some of which can be quite large, or interesting
in other ways.
This cache is a 200ml Sistema container, hidden in a circular
"park" within the on-ramp loop from Hoddle Street northbound onto
Heidelberg Road. The "park" is an isolated oasis amongst the
traffic, including a small pond.
To get to GZ, approach from the south-west and find a way under
Heidelberg Road. There is no need to cross either Heidelberg
Road or Hoddle Street.