HS2 completes work on 'longest railway bridge'

The bridge allows HS2 to connect its London and Chiltern tunnels.

HS2 engineers have completed construction of what it calls "the UK's longest railway bridge".

The final deck segment of the 2.1-mile (3.3-km) Colne Valley Viaduct, near Denham in Buckinghamshire, was installed on Thursday.

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

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

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

Works started in 2021 when ground engineers began to sink the viaduct's foundations.

A 700-tonne bridge-building machine was launched on site in May 2022 and construction was halfway completed in November 2023.

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

One thousand uniquely shaped pre-cast segments were made at an on-site purpose-built factory, and put into place by engineers using a launching girder.

The final segment featured a plaque with the names of people who worked at the factory and on the bridge.

The installation of railway systems, such as tracks and signalling, will now begin.

Around 200 contractors who worked on the project gathered at the site to celebrate the milestone.

HS2 Ltd senior project manager Billy Ahluwalia said: "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."

HS2 services are due to start between 2029 and 2033, running between the West Midlands and Old Oak Common, west London.