Time Wasting Puzzle - Longest Standard Gauge Trip

["Bill McNiven" <wmcniven@gunzel.ozemail.com.au>]

OK, only bother reading this if you bothered to read the "Longest Broad
Gauge Trip" thread.  (One which I enjoyed a lot! – thanks to Chris
Brownbill.)

Assuming that every standard gauge (1435mm) line that has ever existed is
currently open
and available for traffic, what is the longest possible route you can take
without ever visiting the same
place twice or retracing your route?

I think it starts at Gladstone (S.A.) and ends at Kwinana (W.A.).  The
precise route depends on whether Sydney Central (surface) and Sydney Central
(underground) are considered to be the same place.  My understanding of
Western Victorian SG lines is minimal so there may be some clever routes
there.

Rgds

Bill