The final section of Britain’s longest rail bridge has been lowered into place near London as part of the HS2 project.

The 3.4km-long deck of Colne Valley Viaduct, on which work started in May 2022, just beats the 3.3km Tay Bridge linking Fife and Dundee, which had held the crown of Britain’s longest rail bridge since 1887.

HS2 built 1,000 pre-cast segments at a purpose-built factory on-site. The gently-curved structure stretches across the Colne Valley near the M25 motorway and the village of Denham. It will carry high-speed trains running to and from the capital at speeds of up to 320km/h.

Once the main civil engineering phase of construction ends, the factory and surrounding buildings will be removed, and the whole area between the viaduct and HS2’s 10-mile tunnel beneath the Chiltern Hills just to the north will be transformed into an area of chalk grassland and woodland as part of HS2’s ‘green corridor’ project.

The viaduct is one of 500 bridging structures on the HS2 project that...