Project Overview
Colne Valley Viaduct is one of the most technically demanding and architecturally significant structures within the HS2 Phase One route. Extending 3.4 kilometres across a series of lakes, wetlands and ecologically sensitive habitats, it is now the longest railway bridge in the UK. Its delivery required exceptional precision, advanced construction methodologies and a collaborative approach to engineering problem‑solving.
Kilnbridge played a central role in the successful realisation of this landmark structure, delivering the reinforced concrete foundations, piers and associated precast elements that form the viaduct’s primary load‑bearing system. The company’s contribution demonstrates its capability to execute complex civil engineering works at scale, while maintaining industry‑leading standards of safety, quality and environmental stewardship.
Kilnbridge’s role encompassed the construction of 58 reinforced concrete piers, including the viaduct’s distinctive V‑piers, which presented a number of challenges due to their geometry, location and architectural requirements. Further, many of these piers were constructed within or adjacent to water, accessible only via a temporary jetty system.
The team delivered large‑scale pile caps of up to 500 m³, constructed within engineered cofferdams to control water ingress and maintain structural integrity. These operations required precise sequencing, continuous monitoring and rigorous quality assurance to achieve the exposed architectural concrete finish demanded by the design team.
To ensure consistency across the viaduct’s complex geometries, Kilnbridge designed and fabricated all formwork in‑house. This allowed the engineering team to refine tolerances, optimise buildability and maintain full control over the interface between precast and in‑situ elements.
A dedicated precast facility was established to manufacture more than 775 precast concrete bridging planks, some weighing over 20 tonnes. These components formed a critical part of the temporary works and access strategy, enabling safe and efficient construction across the viaduct’s length.
Colne Valley Viaduct presented a series of technical challenges that required innovative engineering responses. Working above lakes and wetlands demanded a highly controlled approach to logistics, temporary works and environmental protection. Kilnbridge developed bespoke access platforms, jetty systems and lifting strategies to enable safe construction of the V‑piers without compromising the surrounding habitats.
The viaduct’s exposed concrete finish required exceptional workmanship and stringent quality control. Kilnbridge constructed a full‑scale V‑pier mock‑up to test formwork systems, concrete mixes, curing regimes and finishing techniques before full production commenced.
The V‑piers required millimetre‑accurate alignment to interface with the precast deck segments which were installed by ‘Dominique’, a 700t launch girder that was used to place the 1,000 unique pre-cast elements that made up the final bridge. Kilnbridge’s engineering and surveying teams implemented advanced digital modelling, real‑time monitoring and iterative verification processes to achieve the required tolerances.
Producing hundreds of unique precast elements demanded a highly coordinated manufacturing and logistics operation. Kilnbridge’s in‑house capability ensured consistent quality, reduced programme risk, and improved integration with the wider Align JV delivery strategy.
Safety was a defining priority throughout the project. Kilnbridge implemented a comprehensive safety management system tailored to the unique risks of working above water, handling large precast elements and delivering heavy civil engineering works in a live construction environment.
This saw the team achieve zero major incidents across the pier construction programme, implement a bespoke lifting plan for all V‑pier and precast operations, introduce enhanced water‑safety protocols, including rescue boat coverage and specialist training and a continuous behavioural safety engagement with a workforce of more than 200 Kilnbridge personnel.
This safety culture was recognised by Align JV and HS2 as a benchmark for high‑risk infrastructure delivery.
Kilnbridge’s commitment to sustainability was demonstrated through innovative reuse of materials and circular‑economy principles.
One such example was the challenge of removing temporary concrete props from beneath the completed bridge structure, which were confined within cofferdams and beyond crane access, Kilnbridge team devised a pioneering solution. By deploying a low-profile skidding system using Hydra-Slide technology, the props were safely slid out and lifted for off-site processing and recycling. Further, concrete waste management was also optimised by transporting intact sections off-site for processing, improving efficiency and reducing on-site handling.
The teams approach and efforts were recognised at the International Green Apple Awards, where the company received an award for environmental best practice.
The Colne Valley Viaduct has been widely celebrated for its engineering excellence, architectural quality, and environmental sensitivity. In addition to the Green Apple Award, the project won the Large Road and Rail Bridge category at the International Association for Bridge and Structural Engineering (IABSE) Awards, which celebrate outstanding bridge engineering worldwide.
Conclusion
Colne Valley Viaduct represents a new benchmark for major UK infrastructure – technically advanced, environmentally responsible and architecturally significant. Kilnbridge’s role in delivering the viaduct’s foundations, piers and precast elements showcases the company’s ability to solve complex engineering challenges through innovation, precision and disciplined project management.
With a proven track record in safety, sustainability and large‑scale civil engineering, Kilnbridge has demonstrated its capability to deliver nationally significant infrastructure with excellence. The company’s contribution to Colne Valley Viaduct reinforces its position as a trusted engineering partner for the most demanding and high‑profile projects in the UK.
