Hopefully there is a train driver on these forums who can give you a definate answer. However, what I can tell you is this.
Use the forums on this site http://www.railpage.com.au/ (the site is down at the moment). Join the forums and ask questions to actual train drivers.
Secondly, I have done a little research on this myself and I will tell you to expect anything from $42,000-$48,000 for a starting wage. If you put in an extra day in every two weeks or so, you may make between $52,000-$58,000 depending on what shifts you can get (weekends and morning/night pay more).
In other words, if you put in a few more hours a month you can make a very nice wage. Just be warned, this is a heavily unionised job.