HS2 tunnellers hit first milestone on longest drive – video - Construction Enquirer

Chiltern tunnel twin drives make first ventilation shaft after 3.6 miles dig

Together TBMs Florence and Cecilia have dug a combined total of over 3.6 miles to the 78m deep ventilation shaft at Chalfont St Peter – the first of five that will provide ventilation and emergency a… [+1068 chars]

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