HS2’s tunnelling machines reach Chalfont St Peter ventilation shaft

The two giant tunnel boring machines that set off just inside the M25 last summer heading north out of London have completed the first stage of their tunnelling, having reached the ventilation shaft close to Amersham.
This achievement means that a combined total of over 3.6 miles has now been dug by the two machines – named Florence and Cecilia – since they launched from the southern end of the tunnels last summer.
The 78m deep shaft, about halfway between Amersham and Chalfont St Pe