The UK’s HS2 high-speed rail project has completed construction of the country’s longest rail bridge after lowering the final deck segment of the 3.4km Colne Valley Viaduct into place.

The structure, one of the largest pieces of infrastructure built for HS2, will carry trains across the valley by the M25 motorway and has taken just over two years to complete, with work beginning in May 2022.

HS2 Ltd’s senior project manager Billy Ahluwalia said: “Lowering the Colne Valley Viaduct’s final deck segment into place today marks the culmination of more than ten 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.”

The new rail bridge takes over from the 3.3km Tay Bridge as the UK’s longest after almost 140 years of the Scottish bridge holding the record and will now move into the rail systems installation phase as part of the HS2 project’s preparations to begin full services by 2033.

Construction of the Colne Valley Viaduct included the placement of 1,000 deck segments across 56 piers, with a 160m-long launcher being used to lower the uniquely designed segments into place.

Once the main phase of construction in the area, which includes a ten-mile tunnel through the Chiltern Hills, comes to an end, HS2 will work on restoring the area overtaken by its construction infrastructure into an area of chalk grassland and woodland. 

The successful completion of the bridge will be welcome good news for the HS2 project, which has been marred by controversy over price, delivery time, and its environmental impact since it began development in 2009.

Most notably, the UK’s former Prime Minister Rishi Sunak scrapped half of the project when he ended plans to continue the high-speed railway line between London and Birmingham on to Manchester, leaving a parliamentary committee to later declare the move meant the project now represented “very poor value for money”.