HS2 ground engineers have begun the foundational work on the project’s carbon saving Wendover Dean Viaduct, seeing a team sinking the first of more than 50 concrete pillars which will form the foundations.
This pioneering viaduct will stand at 450m-long and comes as the first major railway bridge in the UK to be built with a ‘double composite’ structure. Coming as a more environmentally sustainable design, compared to the more traditional infrastructure used in similar projects, HS2 are using significantly less carbon-intensive concrete and steel.
Carbon reduction comes as a key area of focus within this construction process, adhering to the Governments decarbonisation ambitions to achieve net-zero within the sector. Instead of using solid pre-stressed concrete beams to form the bridge spans, steel girders will b sandwiched between two layers of reinforced concrete to create a lightweight and super strong hollow span. This approach is set to save an estimated 7,433 tonnes of embodied carbon within materials– the equivalent of someone taking 20,500 return flights from London to Edinburgh.
HS2 Ltd Project Client Rohan Perin said:
“HS2 trains will be zero-carbon from day one, offering a cleaner, greener way to travel, 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 innovative design will help us cut our carbon footprint while delivering a lighter, stronger, and more elegant structure.”
53 concrete piles will come together to form the foundations of the structure, ranging in sizes from between 38 and 46m deep. Holes will be bored before being backfilled, instead of hammering the piles into the ground. HS2’s main work contractor, EFKB EKFB - a team made up of Eiffage, Kier, Ferrovial Construction and BAM Nuttall – will work over this summer to construct these piles for the project.
A project of this size can often cause local disruptions around the affected areas, something which HS2 have been keen combat, wherever possible, over the course of their many construction schemes. With this in mind, the piers used for the infrastructure will be cast as shells before being assembled on site and filled with concrete.
EKFB Senior Engineer James Collings said:
“We’re delighted to commence the next stage of construction with the bored piling works. The team has worked hard to deliver the preparatory works ahead of this stage. We’ve also been busy constructing the pier platform for the North side of the viaduct.
“The Wendover Dean Viaduct will sit narrowly between two hills, spanning 450m across, and its design is pioneering, conveying a lightweight structure benefiting from less concrete and steel being used in the construction process.”
Coming alongside the environmental benefits throughout the construction, the completed structure design will reduce its silhouette across the valley due to nine evenly spaced piers. These will support the deck of the viaduct and will be placed to carefully reflect the near symmetry of the ground beneath.
Once construction is complete, the historic field boundaries and hedgerows will be recreated to provide uninterrupted access for farmers and local residents. 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.
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