HS2 finishes 'UK's longest railway bridge'

The bridge will carry high-speed trains 10m above the surface of Colne Valley lakes, River Colne and Grand Union Canal

HS2 said it had fully completed work on what it called "the UK's longest railway bridge".

Colne Valley Viaduct, which runs for 2.1 miles (3.3 km), is located near Denham, Buckinghamshire, and is the longest of more than 50 major viaducts being built for HS2.

The high-speed railway will carry trains up to 10 metres above land and water across the Colne Valley between HS2's London tunnels in Hillingdon to the Chiltern tunnels.

Billy Ahluwalia, senior project manager for the viaduct, said: "The completion of the viaduct marks more than 10 years of planning, design and construction."

Construction of the bridge started in March 2021

The Tay Bridge - which is two miles long and links Fife and Dundee - had held the title of the UK's longest railway bridge since 1887.

The new viaduct stretches across the Colne Valley near the M25 motorway.

Trains will travel at about 200mph on the viaduct's curve, which is formed of 1,000 uniquely-shaped deck segments, HS2 Ltd said.

Mr Ahluwalia added: "It's a remarkable achievement. The viaduct is a structure of international significance, a stunning feat of engineering that will no doubt stand the test of time."

The last of the giant pre-cast deck segments was lowered into place in September 2024

Work was managed by contractor Align JV, which consists of infrastructure companies Bouygues Travaux Publics, Sir Robert McAlpine and VolkerFitzpatrick.

Align had been installing parapet sections, noise barriers, a structural health monitoring system and waterproofing and drainage since the final segment was lowered into place in September 2024.

Coralie Peroux, project director at Align JV, said: "I'm immensely proud of the Align team and our supply chain partners.

"Faced with the technical challenges in design and construction, they harnessed their expertise, worked as an integrated project team, and embraced collaboration," she added.

HS2 Ltd said it aimed deliver the railway "in the most efficient way" for "the lowest reasonable cost".