Civil engineering works on HS2’s Colne Valley viaduct – the UK’s new longest rail bridge – have been completed.
The 3.4-kilometre-long structure carries Britain’s new high-speed railway across a series of roads, lakes, the River Colne and the Grand Union Canal, northwest of London. Trains will operate at 320km/h on the viaduct’s gentle curve, which is formed of 1,000 uniquely shaped deck segments.
Advertisement
Construction of the ten-metre-tall viaduct started in March 2021, led by HS2’s main works contractor for this section of the route, Align, a joint venture between Bouygues Travaux Publics, VolkerFitzpatrick and Sir Robert McAlpine. The last of the giant pre-cast deck segments was lowered into place in September 2024.
Since then, Align has been putting the finishing touches to the new landmark. This includes installation of parapet sections, noise barriers, a structural health monitoring system and waterproofing and drainage.
Advertisement
It means that the Tay Bridge, which links Fife and Dundee, has finally ceded the crown of Britain’s longest rail bridge, a record it had held since 1887.
Although it marks a significant achievement on this section of the railway, far more work is needed to bring civil engineering to the same level of completion elsewhere on the 225-kilometre route between London and the West Midlands. Mark Wild, HS2’s chief executive, is now leading a comprehensive reset of the programme to deliver the railway in the most efficient way possible and for the lowest reasonable cost.
Advertisement
‘The completion of the viaduct marks more than ten years of planning, design and construction,’ said Billy Ahluwalia, HS2’s senior project manager for the viaduct. ‘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.’
‘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,’ said Coralie Peroux, Align JV project director. ‘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.’
The viaduct stretches across the Colne Valley near the M25 motorway and the village of Denham. It sits between the 13.5-kilometre Northolt Tunnel, which carries HS2 services beneath London, and the 16-kilometre Chiltern Tunnel. It’s the longest of more than 50 major viaducts being built for HS2.