We are working on the scheme as part of Align, our joint venture with international infrastructure specialists Bouygues Travaux Publics and VolkerFitzpatrick, which has been contracted to deliver the HS2 Central 1 (C1) package.

C1 consists of 21.6km of high-speed rail infrastructure including a 3.37km viaduct, 16.04km twin-bored tunnel and five vent shafts handling both intervention and tunnel ventilation facilities.

Significant work has already started at Align’s main site, the South Portal, which is located to the West of London just inside the M25 and covers 136 acres.

Dedicated motorway slip-roads have been built to link the new site with the M25 and take construction traffic off local roads. As you can see from the pictures, excavation is already well under way of the launch site from which two 2,000 tonne, 170m long tunnel boring machines will start their journey under the M25, excavating the twin bore Chilterns tunnel through Buckinghamshire.

Work is also under way on the construction of a concrete precast plant where the 118,000 tunnel segments, each weighing on average 8.5 tonnes, will be made.

Spoil from the tunnels will be pumped as slurry back to a treatment plant, also currently under construction, where it will be treated before it is used for landscaping on-site.

Just south of the main site will stand the Colne Valley Viaduct, which will be the longest railway viaduct in the UK at 3.4km long. It will carry HS2 across the Grand Union Canal and surrounding lakes. The 1,000 segments required for the viaduct will also be made on site at the South Portal and a separate batching plant is under construction.

Find out more about HS2

HS2 completes civil engineering works on longest tunnel

23 Jan 2026

The close of work on the tunnel's vent shafts brings an end to a project our Align JV began almost five years ago

Significant HS2 milestone as Chiltern Tunnel complete

07 Aug 2025

The construction of the 10-mile tunnel by our Align JV finishes ahead of schedule

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

Final phase of Hexham hospital redevelopment completed

18 Feb 2026

Phase 3 delivered state-of-the-art operating theatres, modernising surgical facilities to support high-quality, modern care

NAW: Apprentices at Agratas

13 Feb 2026

Administration Apprentice, Maisie Woods, a resident of Bridgwater, is amongst the ten apprentices employed by Sir Robert McAlpine currently working at Agratas

Major construction milestone reached at Agratas

11 Feb 2026

Agratas, Tata Group’s global battery business, has announced the successful completion of the steel frame for its new facility in Bridgwater, Somerset.

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Work progressing on HS2