After three years of construction, the deck of the Colne Valley Viaduct on HS2 in Buckinghamshire has been completed to break a 137-year-old record as Britain’s longest railway viaduct.
The final deck segment was lowered into place on Thursday, 5th September as the culmination of the installation of 1,000 segments that were pre-cast at a purpose-built factory on-site.
The gently curving structure stretches 2.1 miles across the Colne Valley near the M25 motorway and the village of Denham, and now supersedes the Tay Bridge as Britain’s longest railway bridge.
The viaduct is one of 500 bridging structures on HS2 that include footbridges, drainage culverts, and innovative ‘green bridges’ for wildlife.
Construction of the viaduct is being managed by the main works contractor Align JV comprising Bouygues Travaux Publics, Sir Robert McAlpine, and VolkerFitzpatrick.
Work on the deck started in May 2022, since when the bridge’s 1,000 uniquely shaped deck segments have been lowered into place using a massive 160-metre-long launching girder.
Supported on the viaduct’s 56 piers, the launcher used a balanced-cantilever method to edge forward from north to south and lower deck segments into place to form half an arch on either side of a pier. The launcher then repeated the process by moving to the next pier to complete the arch span.
A factory to construct the 1,000 pre-cast segments was purpose-built on-site. Each segment is uniquely shaped so that the structure curves as it carries HS2 up to 10 metres above the Colne Valley.
After completion of the main civil engineering phase, the factory and surrounding buildings will be removed and as part of HS2’s ‘green corridor’ project the whole area between the viaduct and a 10-mile tunnel underneath the Chiltern Hills just to the north will be transformed into an area of chalk grassland and woodland.
Completion of the Colne Valley Viaduct comes just one week after HS2’s first major viaduct, at Highfurlong Brook in Northamptonshire, was completed.
Work is also progressing on the Delta Junction viaducts in the West Midlands and the elevated approaches to Curzon Street station in Birmingham.
“Lowering the Colne Valley viaduct’s final deck segment into place today marks the culmination of more than 10 years of planning, design and construction. I pay tribute to the dedicated team that has delivered a bridge that is both the longest on HS2 and has become the United Kingdom’s longest railway bridge – taking a record that had stood for nearly 140 years. That is a historic achievement of which we can all be immensely proud.”
Billy Ahluwalia, HS2 Ltd senior project manager
“The Align team, along with our supply chain partners VSL who operated the launching girder, have worked very hard to get us to where we are today, ahead of plan. Working together and as a truly integrated team that includes HS2, Align, our design partners, our supply chain colleagues and the local community, we have built the Colne Valley Viaduct which will be the iconic feature of HS2.”
Loïc Menard, Align Project Director
Responses
Surely the London Bridge to Greenwich viaduct, built in 1836, at 3.4 miles long is not only the longest but the oldest railway viaduct in the UK?
HS2 as an engineering project is great. Sadly as a practical railway it has always been flawed . A political folly which can join many other global vanity projects like unused airports and olympic stadiums rotting away dreaming of what could have been.
Talking about a ‘green corridor’ is just a load of greenwash. The amount of CO2 produced in the production of all that concrete is phenomenal, just to knock a few minutes off the rail journey.
Incredible…. It equates to the Pyramids or more.
A magnificent engineering achievement but avery expensive way of lengthening the journey from London to Birmingham.