High Speed Two (HS2) has confirmed the completion of the Colne Valley Viaduct, which is being described as the “longest” railway bridge in the UK.
The structure measures 2.1 miles and is one of over 50 major viaducts being constructed as part of the HS2 initiative.
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HS2 senior project manager for the viaduct Billy Ahluwalia said: “The completion of the viaduct marks more than ten years of planning, design and construction. I’m immensely proud of the level of dedication and professionalism shown by the whole team to maintain high standards of safety and quality, working over land and water to deliver.
“It’s a remarkable achievement. The viaduct is a structure of international significance – a stunning feat of engineering that will no doubt stand the test of time.”
Situated near Denham in Buckinghamshire, the viaduct will facilitate the new high-speed railway’s passage over various terrains, including roads, lakes, the River Colne, and the Grand Union Canal, to the north-west of London.
Trains are expected to travel at speeds of 200mph along the viaduct, which features a gentle curve made up of 1,000 deck segments.
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By GlobalDataConstruction began in March 2021, with Align, a joint venture (JV) involving Bouygues Travaux Publics, VolkerFitzpatrick, and Sir Robert McAlpine, overseeing the works for this section.
The last precast deck segment was placed in September 2024, it was reported.
Following this, Align has been working on finalising various elements of the structure, including the installation of parapet sections, noise barriers, a structural health monitoring system, as well as waterproofing and drainage solutions.
Align JV project director Coralie Peroux said: “I’m immensely proud of the Align team and our supply chain partners, not just for successfully completing the UK’s longest rail bridge, but for the remarkable way they delivered it.
“Faced with the technical challenges in design and construction, they harnessed their expertise, worked as an integrated project team, and embraced collaboration. Their efforts have produced a striking HS2 landmark and created a valuable learning legacy for future designers, engineers and construction professionals.”
With this development, the Tay Bridge, which has connected Fife and Dundee, has now been surpassed in length, a title it held since 1887.
While HS2 has acknowledged this as a notable accomplishment for this part of the railway, the company has also indicated that extensive work is still required to advance civil engineering efforts along the 140-mile route linking London and the West Midlands.
The viaduct is located between the 8.4-mile Northolt Tunnel, which runs beneath London, and the ten-mile Chiltern Tunnel.
