After almost 140 years, Britain has a new longest rail bridge. On Thursday 5 September the final sections of HS2’s Colne Valley viaduct were lowered into place, completing the 3.4 kilometre (2.1 mile) long structure on London’s north-western edge. It will eventually carry high speed trains running to and from the capital at speeds of up to 320km/h (200mph). The viaduct’s completion means that the 3.3km Tay Bridge linking Fife and Dundee has finally ceded the crown of Britain’s longest rail bridge to HS2, a record it had held since 1887. Work on the deck of the viaduct commenced in May 2022. Over a period of 28 months, a specialised team of engineers used a massive launching girder to position 1,000 uniquely-shaped deck segments. Supported by 56 piers, the viaduct stretches across the Colne Valley, carrying the HS2 line up to 10 metres above land and water. Each of the 1,000 segments was precast on-site in a purpose-built factory, with every piece specially shaped to allow the viaduct to curve smoothly across the landscape. Once the civil engineering phase is complete, the factory and surrounding buildings will be dismantled, and the area between the viaduct and HS2’s 10-mile tunnel under the Chiltern Hills will be restored to chalk grassland and woodland, as part of HS2’s ‘green corridor’ initiative. The project is now set to transition into the rail systems installation phase, with the viaduct expected to become operational between 2029 and 2033. Once HS2 is fully operational, high-speed trains will link London and Birmingham, significantly reducing journey times and freeing up space on existing rail lines for local and freight services. Billy Ahluwalia, Senior Project Manager at HS2 Ltd, commented: “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.” Loïc Menard, Align Project Director, added: “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.” This milestone follows closely on the heels of HS2's completion of its first major viaduct at Highfurlong Brook in Northamptonshire. Progress is also being made on the Delta Junction viaducts in the West Midlands and the elevated approaches to Curzon Street station. Where: Colne Valley, Hertfordshire, United Kingdom When: 05 Sep 2024 Credit: HS2/Cover Images **EDITORIAL USE ONLY. MATERIALS ONLY TO BE USED IN CONJUNCTION WITH EDITORIAL STORY. THE USE OF THESE MATERIALS FOR ADVERTISING, MARKETING OR ANY OTHER COMMERCIAL PURPOSE IS STRICTLY PROHIBITED. MATERIAL COPYRIGHT REMAINS WITH STATED SUPPLIER.**