'Every millimetre counts': Inside the beast tunnelling under Sydney Harbour (smh.com.au)

I'd never thought about it till a knee jerk scoffing at the title:

But do they need the TBM to be milimeter accurate the whole way- or do they just need mm accurate surveying and very high accuracy when merging the tunnels?

It might seem inane- but they're two VERY different things.

Interesting to a see a Windows 7 machine in the picture captioned "Andrew Jones in the boring machine’s control room."

Yay for the metric system!