This may have been mentioned on Railpage forums before although I can't seem to find it. I've read somewhere on the internet that there could be as many as 9 railway tunnels under Redfern station. The one currently in use is the cross track dive tunnel that goes from Eveleigh Railyards to Central. There are actually two half constructed and disused platforms know as platform 13/14 and being underground platforms they would have tunnels leading to the platforms. Other tunnels which are used include the ones going to and from platform 11/12. I'm wondering if anybody has information about these other tunnels both used and disused, where they come from and where they lead to. What were they originally used for until they were abandoned. This is very interesting as the tunnel network under Redfern is quite complex.

Could the reply please include any photos which may be available for viewing?

http://www.trainman.id.au/photos/nsw/tunnels/

There is a thread on this subject titled "Sydney Southern Suburbs Line Layout Redfern" in the Railway Archaeology forum on this site.
There were at least 10 railway tunnels under the suburb of Redfern (as distinct from the "station") when I last counted them.  I have been unable to confirm whether the still existing pedestrian tunnel linking the former workshops on the north and south side of the main lines ever had rails.  The ramps leading to this tunnel certainly did.

theres also a hole in the wall on the current platforms 11/12 where you can take a peak at the abandoned platforms 13/14. Not really much to see except grass and a wall but hey its there if u want to check it out