St. James Disused Subway Tunnels
Sydney has several disused subway tunnels. The most well-known of these are those leading of St. James station. St. James station was designed to support four tunnels, but only two were ever constructed. The remaining two are stubs, which lead some way off from the station but then abruptly end. The intention behind this was that if they later decided to use these tunnels, they could extend them without causing interference with St. James station, thus permitting it to remain in operation. However, due to changes in the State Government's transportation plans over the last eighty years, the tunnels are unlikely to ever be extended to go somewhere.
Despite not going anywhere, they have still seen a significant amount of use over the years. This has included use as a mushroom farm (prior to the construction of Circular Quay station, the main tunnels heading there were disused as well; all four tunnels in that direction were leased by the State Rail Authority to a mushroom farmer) and a World War II bomb shelter. According to legend, US General Douglas Macarthur had his headquarters in these tunnels before moving to Townsville; but no evidence of this exists today. (Some think the headquarters are still there, but have been bricked or concreted off from the tunnels; but it is more likely that they were located in the tunnels, and no evidence remains of them today.)
The two disused tunnels lead off both to the north and south of St. James station, in between the two tunnels currently in use. The platform of St. James Station is in fact two platforms, with a space separating them for the tunnel tracks; but this space has been covered over with a false floor, giving the appearance of a single platform. (The false floor in fact has drainage pipes and power cables running under it, and one can crawl underneath it.)
The tunnels are divided into sections by concrete walls that were constructed in World War II to protect against bomb blasts. They also have interesting passages running between them, designed to stop the force of an explosion in one chamber travelling into the adjacent chambers.
Immediately after World War II, the soldiers who had run the bomb shelters in the tunnels were set to work demolishing them, primarily to give them something to occupy themselves with until they could be demobilised. But the work was never completed; several of the chambers in the tunnels still contain piles of rubble the soldiers left behind. They also left graffiti on the tunnel walls, and you can still read graffiti from the 1940s today (along with a few more recent contributions).
Other interesting uses for the tunnels have included its use by ABC (Australian Broadcasting Corporation) sound engineers in the 1960s to fake the sound of Big Ben for a TV series. The large bell they used to do this still sits in the tunnels today. They also used it to film one episode of the early 1990s Australian TV series "Police Rescue". They painted some colourful and rather nasty looking graffiti on one of the walls separating the bomb shelter chambers, to serve as a backdrop to the climax of the episode (the rescue of a boy lost in a storm water drain). (Later a journalist for a Sydney tabloid newspaper saw this, and found three women who were willing to say they painted it as part of their witches coven underneath Sydney; unfortunately for the newspaper this proved somewhat embarrassing when the ABC admitted they had done it.)
At the southern end the tunnels grow progressively narrower, and begin to rise above the two tunnels currently in use, at one point passing directly underneath the Bondi Junction line, until they finally reach a dead end. In the northern direction, the tunnels open up into a chamber, roughly underneath NSW State Parliament and the NSW State Library, that ends in a large rock face; this however is not the end of the tunnel. Two smaller passages lead into the rock face; one at floor level which extends only a few meters before ending, the several meters above the tunnel floor which passes through the rock face before opening at another chamber at the other side.
From the chamber opposite the rock face a shaft leads directly up to Shakespeare Place (which is just a small segment of road between the State Library and the Botanic Gardens). This is because the tunnel was originally built from two directions, one from St. James station in the South and the other from Shakespeare Place in the north; however the two segments of the tunnels were never properly joined, being connected just with a small passageway. During World War II a stair case lead down the shaft from street level into the tunnel; the staircase was long ago removed and the shaft covered over at street, though looking up from below thin cracks of sunlight can still be seen around the edges of the shaft.
The chamber ends in a lake, which has been nicknamed "Lake St. James". This lake has been formed by water seeping down from the Botanic Gardens irrigation system, the Botanic Gardens being directly above it. Eels are reported to live in the lake, though no one knows how eels found their way into a disused subway tunnel. The lake is quite large, disappearing out of sight around a bend in the chamber. It continues past the bend for about 50 metres then ends in abruptly in a rocky, half-completed face. The end section of the tunnel is interesting - the lower half of the face looks more finished and is flooded quite deeply - hard to tell how deep, perhaps several metres. There is a ladder leading out of the flooded section into the small, uncompleted rocky alcove at the top, which you can climb into if you want to be covered in some really filthy, old mud. It extends for about 3 metres. From here you can shine your torch back into the tunnel and create some interesting light effects from the distortion effect of the tunnel and the clear, light bluish water. As well as the lake, a lot of the other chambers of the tunnels at both ends are flooded, but only shallowly - maximum 2 foot deep.
When you are at the start of the tunnel, note the narrow rail tracks running into the water. They go all the way to the end. It would be worthwhile diving to the bottom of this tunnel at the end and investigating whether the end of this tunnel does indeed end abruptly, as there are some interesting sections vaguely discernible from the water surface. I don't know about the water quality or the eels, but it looks pretty clear.
Tours of the tunnels have at times been run by the Australian Railways Historical Society, with the approval of the State Rail Authority. Many others have been visited them unofficially (and illegally), by walking down the used subway tracks until passages leading between the used and disused tunnels are reached. (Part of the disused tunnels is used to store rail service vehicles, and there are railway sidings connecting them with the main tunnels, as well as numerous pedestrian passages.) Accessing them via the used tunnels is rather dangerous, although so long as one understands the meaning of the tunnel safety lights one is in far greater risk of being arrested than of being run over by a train. The official tours access the disused tunnels by much safer means, by doors located on the platforms, but these doors are normally kept locked.
Other Disused Subway Tunnels
As well as the St. James subway tunnels, there are several disused tunnels and platforms on the Bondi Junction line, which like St. James station provided for the possibility four tunnels even though only two were ever built. Most of the stations have these disused platforms adjacent (but walled off from) the platforms currently in use. At Redfern station instead of platforms there is a big open pit in the ground, running from surface to subway level, which in 2000 construction personnel were busy building something in (possibly a car park). The abandoned platforms at Central are used to store the Archives of the State Rail Authority. Like St. James, these stations have stub tunnels, although they are much shorter.
It is possible to access the Redfern pit in the ground and disused tunnels by two ways -- there is a hole in the wall opposite the used platforms you can climb through (the one through which you can see sunlight and weeds). It is also reportedly possible to enter the Redfern station stub tunnels from the Everleigh rail yards.
Even though they never were intended to be part of the subway system, one can also mention here the tunnels for the old Pyrmont goods line. One of these runs underneath Railway Square, between the Central station railway yards and the Powerhouse Museum; the other tunnel runs underneath Glebe. The first tunnel is not used anymore. The old railway from the Powerhouse Museum to Lillyfield has been converted to form part of the light rail line from Central station. The Glebe tunnel is on this section.
Also of interest is a tunnel connecting the Everleigh rail yards on the southern side of the main line to the northern side of the main line, just past Redfern.