HS2 has begun assembling a viaduct across the floodplain of the River Cherwell near the Oxfordshire border. 

The half-kilometre long Edgcote viaduct will carry the new railway south of Chipping Warden in West Northamptonshire.

Set low into the landscape, the 515m-long viaduct was redesigned last year, copying the approach used at HS2’s Thame Valley, near Aylesbury. 

Instead of five beams per span with concrete poured on site, the viaducts use just two larger ‘u’ shaped beams per span.

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This innovation - inspired by viaducts on the Spanish high speed rail network - will reduce the number of lorry movements and speed up construction by removing the in-situ concrete work.

At between six and eight metres high, the viaduct will be supported by 20 pairs of concrete piers and from a distance, will be largely hidden by current hedgerows and woodland.

Two major new wildlife sites will also be created where the viaduct crosses the floodplain, with new and enhanced fen, marshland and meadow alongside new woodland planting. 

The viaduct passes close to the site of the medieval Battle of Edgcote. Fought on July 26, 1469, during the Wars of the Roses, the battle is thought to have taken place on the nearby Danesmoor.

Archaeological investigations have not found any evidence of the battle at the site.

Edgcote and Thame Valley are among more than 50 major viaducts being built as part of the HS2 project.

The 210m long Lower Thorpe Viaduct, two miles to the south of Edgcote viaduct, will also be set low into the landscape.

Seven weathered steel spans will carry the railway across Banbury Lane just south of the village of Thorpe Mandeville.

The last few weeks have also seen the project’s first viaduct - at Highfurlong Brook in Northamptonshire – completed and the deck assembly at the Colne Valley Viaduct in West London finished, which has now become the longest railway bridge in the UK.

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It comes as Transport Secretary Louise Haigh has announced a major review into the spiralling costs of HS2.

The stated cost is currently £66 billion, however HS2 Ltd provided an upper limit projection of £74 billion in 2023.

The Department for Transport said the cost of the rail project "soared, due to poor project management, inflation and poor performance from the supply chain".

The new Labour government has launched an independent review to be carried out by James Stewart, the former chief executive of Infrastructure UK who worked on the Crossrail project in London.

Regular meetings will also start immediately between the Transport Secretary, Rail Minister Lord Hendy and the Chief Secretary to the Treasury on the progress of the project and its costs.