Time Wasting Puzzle - Longest Broad Gauge Trip

[Chris Brownbill <cbrnbill@enternet.com.au>]

OK, only bother reading this if you've got some time to spare and a really good
knowledge of Australia's broad gauge rail network through history.

Imagine you are organizing a fan trip.  You have a broad gauge (1600mm) train,
and gloriously, every broad gauge line that has ever existed is currently open
and available for traffic (dream on).

What is the longest possible route you can take without ever visiting the same
place twice or retracing your route?

I do have a solution worked out, but I wonder if anyone can get greater
coverage.

Hint - start at Peterborough (SA) and end at Orbost (Vic).

The great thing about broad gauge is historically the huge number of
cross-country lines which make the number of alternatives here so great.