Japan's Largest Shield Tunnel

It's 1400hrs on Thursday the 3rd of July and we are waiting in front of the Hachiko statue, ready to be taken to see Japan's largest shield tunnel. Whilst waiting for everyone to arrive, we noticed a small white cat had been placed under Hachiko...

Cat-chiko (hahaha...*ahem*)

We walked to Shimizu's offices nearby for a quick slide show about the whole project - mainly about why the tunnels had to be built one on top of another (lack of space) and the issues involved in turning the huge machine around to dig the second tunnel after it had finished the first one.

(left) Shaft 2, where we exited from, you'll notice the whole construction area is covered so that noise and dust does not disturb people near by. (right) down shaft 1, note how close the tunnels are! only 1.5m seperates them and each tunnel is nearly 13m in diameter.

me on the way down shaft 1

(left) the back of the shield tunnel, very clean....(right) the machinery that follows to control the flow of slurry to the face and take away the muck which is dug out. It is currently digging the bottom tunnel.

(left) the tunnel lining - black is ductile cast iron, and white is stiffer steel (right) a complicated s-bend in the tunnel, it is also sloping upwards. - the shield tunnel is programmed to dig this shape and CAD is used to design the individual lining segments...
We emerged at Shaft2. The tunnels only had about 20 or so people working in them (very small work force for such a complex project) it was very clean and well organised - but also very expensive. I am told that the shield tunnelling machine was designed for this project and this project only. After it has finished here, it will be disassembled and then melted for scrap.