HS2 complete UK's longest rail bridge
Contractors working on the HS2 project have completed the Colne Valley Viaduct, making it the UK’s longest rail bridge. The final segment of the viaduct deck was lowered into place last week, marking a key milestone in the development of the high-speed rail network.
The viaduct, measuring 3.4 kilometres (2.1 miles), surpasses the previous record held by the Tay Bridge in Scotland, which has been the longest rail bridge since 1887.
The Colne Valley Viaduct spans the Colne Valley, just northwest of London, near the M25 and the village of Denham. It will eventually carry high-speed trains travelling at up to 320 km/h (200 mph) between London and Birmingham.
The viaduct’s construction has been overseen by the Align JV consortium, comprising Bouygues Travaux Publics, Sir Robert McAlpine, and VolkerFitzpatrick. The team used a purpose-built factory on site to produce 1,000 pre-cast concrete segments, each uniquely shaped to form the curved structure.
The segments were installed over 28 months, beginning in May 2022, using a 160-metre long launching girder. This method, known as the balanced-cantilever approach, allowed engineers to lower segments into place on either side of each of the viaduct’s 56 piers.
“The team has worked incredibly hard to deliver the longest bridge on HS2 and, now, the longest rail bridge in the UK. It’s a historic achievement and a testament to the dedication and skill of everyone involved,” said Billy Ahluwalia, senior project manager, HS2 Ltd.
The next phase of work will focus on installing rail systems as the viaduct moves towards becoming operational, with the first trains expected to run between 2029 and 2033. Once completed, HS2 will connect London and Birmingham, reducing journey times and freeing up capacity on the existing rail network for local and freight services.
The Colne Valley Viaduct is one of around 500 bridge structures being constructed as part of HS2. Other bridges include footbridges, drainage culverts, and wildlife-friendly ‘green bridges.’
Once the civil engineering phase is finished, the area surrounding the viaduct will be transformed into chalk grassland and woodland, contributing to HS2’s ‘green corridor’ project.
“We are ahead of schedule, thanks to the close collaboration between HS2, Align, and our partners,” said Loïc Menard, project director, Align JV. “The Colne Valley Viaduct will be an iconic feature of HS2.”
This milestone follows the completion of the Highfurlong Brook Viaduct in Northamptonshire and ongoing work on viaducts in the West Midlands, including those at the Delta Junction and the elevated approaches to Curzon Street Station in Birmingham.
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