HS2 has reached a major milestone with the completion of civil engineering works on the Colne Valley Viaduct, now officially the UK’s longest rail bridge at 2.1 miles (3.4km).
The viaduct, which will carry high-speed trains at 200mph, stretches across roads, lakes, the River Colne, and the Grand Union Canal northwest of London. It surpasses the Tay Bridge—which held the record since 1887—as Britain’s longest rail bridge.
Constructed by Align, a joint venture between Bouygues Travaux Publics, VolkerFitzpatrick, and Sir Robert McAlpine, the viaduct is made up of 1,000 uniquely-shaped deck segments and stands 10 metres tall. The final segment was installed in September 2024, marking the end of major structural work.
Final touches included:
- Installation of parapets and noise barriers
- A structural health monitoring system
- Waterproofing and drainage systems
HS2 Ltd’s Senior Project Manager for the Viaduct, Billy Ahluwalia, commented:
“The completion of the viaduct marks more than 10 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.”
The viaduct sits between the 8.4-mile Northolt Tunnel and the 10-mile Chiltern Tunnel, forming a key part of the 140-mile HS2 route between London and the West Midlands.
While this milestone is significant, HS2 Ltd is now undergoing a programme reset to deliver the railway more efficiently and cost-effectively. The Colne Valley Viaduct is one of over 50 major viaducts being built for HS2, which will eventually connect London to Birmingham and beyond, easing pressure on the West Coast Main Line and boosting economic growth.
Image credit: HS2 Ltd
Video credit: HS2 Ltd
