HS2 completes 16km Chiltern Tunnel bore

Breakthrough! The first bore of HS2's 10-mile-long Chiltern Tunnel is completed. Courtesy HS2

Tunnel Boring Machine Florence broke through to complete the excavation of one of the two 16km bores for HS2’s Chiltern Tunnel on 27 February. The tunnel is the longest on HS2, with sister machine Cecilia due to complete the second bore in March.

Florence began its journey from the South Portal site near the M25 in May 2021, emerging at the North Portal site at South Heath in Buckinghamshire. In total, 10 TBMs are excavating the 32 miles of tunnel on Phase One of HS2, with four used for the London approach tunnels, two on Birmingham’s Bromford tunnel and two more planned to excavate the Euston tunnel. The Chiltern Tunnel TBMs, made by Herrenknecht in Germany, were operated by main works contractor Align, a joint venture of Bouygues Travaux Publics, Sir Robert McAlpine and VolkerFitzpatrick.

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