Hi mellycat
I'd suggest telling Google to find Google Australia.
Once in Google Australia, tell it to confine its searches to Australian webpages only.
It understands WA, which saves typing Western Australia.
Use every keyword combination you can think of to find either the rail operators or the civil engineering companies who instal and look after the tracks, I suggest.
Here's one:
MVM RAIL Pty Ltd
WA has been found to be stuffed with valuable underground minerals, hence there is a huge iron ore mine and several other mines extracting different things. They all use railways to transport the stuff they have dug up to the coast etc.
You might find that most of the tracks in WA may not be used for passengers.
If you are both under 31 and have no dependent children, one option might be to get yourselves Working Holiday Maker Visas, go out to Oz (unlimited work rights on WHmVs) scout around and take it from there?
Best wishes
Gill