HS2 Colne Valley Viaduct

HS2, Align JV

As a part of the Align joint venture consisting of three international and privately-owned infrastructure companies; Bouygues Travaux Publics, Sir Robert McAlpine, and VolkerFitzpatrick, we are constructing the C1 package of the UK High Speed 2 line (HS2). Not only does this include delivering the record-breaking Colne Valley Viaduct which will be the longest railway bridge in the UK, but we are also constructing HS2’s longest twin-bore tunnel, reaching 10 miles long.

HS2’s giant tunnelling machines, after 3 years – broke through at the end of their 10-mile (16km) journey under the Chilterns, excavating the longest tunnel on the ambitious HS2 rail project.

Constructing the ten mile tunnel under the Chiltern Hills

Two enormous 2,000 tonne tunnelling machines dug HS2's longest tunnels passing five ventilation shafts and completing a 10 mile drive under the Chilterns. Each machine was a 170m long self-contained underground factory, digging the tunnel, lining it with concrete segments to form rings and grouting them into place as it moves forward.

HS2 will almost halve journey times between Britain’s two largest cities, while freeing up space for more local services on the most crowded part of the existing West Coast Main Line.

HS2’s viaduct across the Colne Valley has traversed the Grand Union Canal on its way to becoming Britain’s longest railway bridge. In total, 56 piers have been built to carry the viaduct. Piers need to be built in advance of the deck being laid. We are using a giant launching girder to install the viaduct’s 1,000 deck segments, with the machine making its way from north to south across the Colne Valley to position them into place.

Delivering the UK’s longest railway bridge

HS2’s 2.1 mile (3.4km) Colne Valley Viaduct will be UK's longest railway bridge when complete

The Align JV began constructing the bridge in early 2021, forming the foundations for the Colne Valley Viaduct. In Spring 2022, an enormous 700 tonne bridge-building machine was launched on site. Known as a ‘launching girder’, the machine is used to lift the giant concrete deck segments that form the viaduct’s arches into position. 56 piers each weighing around 370 tonnes have been constructed ahead of the girder.

In November 2023 main construction of the bridge officially passed the half-way mark. Once construction is complete, the factory and surrounding buildings will be removed and the whole area between the viaduct and the Chiltern tunnel will be transformed into an area of chalk grassland and woodland as part of HS2’s ‘green corridor’ project.

This is a complex project however we have delivered some unique innovations to address the engineering challenges relating to both design and planned construction of the tunnel, the tunnel shafts and the viaduct. It’s both rewarding and exciting to get the construction element of the project underway.

Daniel Altier, project director of Align


Delivering social value

More than 27,000 jobs have been supported by HS2, which is designed to transform transport links between Britain's major cities, free up space on the rail network for more freight and local services and support the UK's transition to net zero carbon emissions.

Through our engagement work we aim to offer help or solutions that enhances the lives and wellbeing of the residents, the environment and society in general.

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