Our Align JV are celebrating following the completion of construction for the highly complex Chiltern Tunnel.

The Align team congregate for a picture upon the completion of the Chiltern Tunnel work

The five-year programme involved construction of the 10-mile tunnel, the longest on the HS2 route, the South Portal porous portal structures and accompanying earthworks trace.

Align is our HS2 joint venture with Bouygues Travaux Publics and VolkerFitzpatrick.

Works began in 2020 with the iconic tunnel boring machines (TBMs), Florence and Cecilia, commencing their journeys in spring 2021. Their typical drive is 5-6km, so this circa 16km drive required some technical innovations never used before in the UK.

Since the breakthroughs of the TBMs at the North Portal in early 2024, the team have been finishing the 38 cross passages and 5 adits, the strip out of services and slurry pipes, slipforming the emergency walkways, completing construction of the South Porous Portals and constructing the crossover slabs and drainage for the train track.

The portals are built to eliminate the possibility of ‘sonic boom’ being created by high-speed trains entering at 200mph, a first for the UK rail network.

Through the project's close teamwork and collaboration, the programme was completed 12 days ahead of the contractual date.

An incredibly complex project, it has won multiple awards and showcased some pioneering engineering expertise.

Find out more about HS2

Colne Valley Viaduct scoops two NCE Bridges awards

05 Aug 2025

Iconic structure forms part of the HS2 project being constructed by our Align JV

Unique HS2 tunnel portal completed

25 Apr 2025

Our Align JV builds tunnel extensions for HS2 to stop sonic booms from 200mph trains entering the 10-mile Chiltern Tunnel.

HS2 Colne Valley Viaduct wins design award

26 Nov 2024

Colne Valley Viaduct named winner in the 'engineering' category  of the Royal Fine Art Commission Trust’s Building Beauty Awards - 2024 

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