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.