HS2 claims its new viaduct design will halve carbon emissions on Wendover project

The project director says HS2 is 'serious' about reducing the amount of carbon it uses.

Thursday, 22nd July 2021, 11:50 am

HS2 claims its designers are on track to develop a new viaduct system which will halve carbon emissions on the Wendover rail project.

HS2 says it is using a ‘double composite’ approach, involving two steel girders sandwiched between two layers of reinforced concrete to create a super strong but lightweight span.

The viaduct in Wendover was recently approved by the Bucks Council, who said it could do 'nothing' to block this submission.

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How the Viaduct should look on completion
How the Viaduct should look on completion

The viaduct was approved under Schedule 17 of the HS2 Act, it is claimed that it will be the first major railway viaduct in the UK to use the ‘double composite’ approach.

The 450m viaduct is one of 50 being built on the first phase of HS2 between London and the West Midlands.

HS2 designers are applying lessons from the use of double composite structures on the latest French TGV lines. HS2 says its team has cut the amount of embedded carbon in the viaduct by 7,433 tonnes – the equivalent of 20,500 return flights from London to Edinburgh.

Other environmentally friendly features it is claimed that this viaduct has is the slender design which reduces the silhouette of the structure viewed from across the valley. Nine evenly spaced piers will support the deck of the viaduct and will be placed to carefully reflect the near symmetry of the ground beneath.

HS2's latest design from another angle

Another innovation HS2 is claiming is the piers – some of which will be up to 14 metres high – will be cast in pieces offsite before being assembled like giant lego blocks.

HS2 Ltd’s project client director Ambrose McGuire said: “By providing a cleaner, greener way to travel, HS2 will help cut the number of cars and lorries on our roads, cut demand for domestic flights, and help the fight against climate change.

“But we’re also serious about reducing the amount of carbon we use during construction, and Wendover Dean is a great example of how we’re using the latest engineering techniques to do just that. Concrete is one of the construction industries’ biggest sources of embedded carbon – and this design will help us cut our carbon footprint while delivering a lighter, stronger and more elegant structure."

The design of this viaduct has been handled by HS2 Ltd’s main works contractor, EKFB - a team made up of Eiffage, Kier, Ferrovial and BAM Nuttall - working with their design partner, ASC (a joint venture between Arcadis Setec and COWI) and specialist architects Moxon.

EKFB’s technical director Janice McKenna said: "This viaduct was inspired by the innovative design in France, but has been enhanced and developed in the context of the Chilterns. Our design solutions are always created with people and legacy in mind and I am really proud of the carbon savings that the Wendover Dean Viaduct represents.”

The beams themselves will be made from weathering steel, it will age to a dark russet finish. The total steel weight is around 1400 tonnes and will be topped with a concrete deck which will carry the track and built-in noise barriers.

The viaduct peers have been extended to almost connect with the parapet, helping to give the appearance of a light and narrow structure, designers say.

A mix of trees and shrubs commonly found across the Chiltern chalk hills will be used for new woodland planting around the viaduct, including Oak, Beech, Hazel and Wild Cherry, HS2 says.