After HS2’s first tunnel breakthrough by TBM Dorothy at the south portal site in July this year, the front part of the TBM has been dismantled and transported back to the tunnel’s north portal in a 24/7 intricate operation, managed by the plant and logistics team at HS2’s contractor Balfour Beatty VINCI (BBV).  

The cutterhead, weighing 160 t and with a 10-m diameter, was moved during the night of Wednesday 21 September. Standing upright on a 12 m-long, 48-wheel Self Propelled Trailer (SPT), it was transported from the south portal site, along the A425, through the village of Ufton and onto HS2’s north portal site.  

The TBM's 120 t tail skin, also 10 m in diameter, was also moved in the same operation. The 2.5-mile journey took 180 minutes, with the loads arriving at their destination at 03.00 hours on Thursday 22 September. 

Eight other large pieces from the TBM’s front shield and middle shield, have already been transported by specialist equipment, which was used specifically to avoid any temporary alterations to the road layout through Ufton.  

The rest of the 120-m long TBM will be pulled back through the one-mile tunnel by a special ‘caterpillar’ system, at a pace of 150 m/day. Once all the parts are back at the north portal, the TBM will be reassembled before starting the second bore later this year.  

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