The diameter of the cutterhead is 7.2 metres. It spins and like an enormous cheese grater shreds rock into gravel and pebbles.

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The shredded rock is mixed with liquid bentonite (a type of clay) to make a slippery slurry that can be pumped to the surface .

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At the surface the bentonite is squeezed out of the slurry and sent back into the TBM to be used again. The dry cakes of dug up material are removed by truck.

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1.6 million tonnes of dirt will come out of the tunnels (that would be enough to fill the MCG right to the top with a peak - just like a giant Dixie Cup!).

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The TBM digs 1.7 metres then stops to line the tunnel. Robotic arms lift six concrete segments into place to form a ring.

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A total of 9370 rings will be installed.

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The tunnel lining segments weigh up to 3 tonnes each. They arrive on a special vehicle and are fed along a conveyer belt to the front of the TBM.

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56,220 concrete segments will be used to line the tunnels.

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The TBM uses hydraulic thrust rams to push itself off the new ring section and starts tunnelling again.

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Our TBMs are electric. Power cords unwind as the machine moves forward. They connect to a substation above ground.

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The TBM’s journey is laser guided. There are always two operators on duty in the Control Room at one time.

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Crews of 15 work around the clock. Together they complete 10-12 metres of tunnel per day.

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In case of an emergency, the Refuge Chamber has room for everyone, plus water, food and an oxygen supply.

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The crew work a 12 hour shift with regular breaks. Their crib has a kitchen and space to chill out.

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Working inside the new tunnel is cleaner than you might think. A fan system delivers plenty of fresh air.

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This is the hidden bonus popup! Well done in finding it, now excuse me I have important business to get to!

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