High Speed Rail company HS2 starts assembly of long viaduct near Banburyshire village

Set low into the landscape of West Northamptonshire, the 515m-long viaduct will carry the new high-speed railway across the floodplain of the River Cherwell, south of Chipping Warden.

HS2 says it is set to become only the second in the UK to have all its major structural elements manufactured off-site ‘helping to speed up construction, boost efficiency and reduce the number of lorry movements on local roads’.

The structure was redesigned last year, copying the approach used at HS2’s Thame Valley, near Aylesbury. This lighter-weight design cuts the amount of concrete and steel in the viaduct, with the piers, beams, deck planks and parapet manufactured off site at a facility in Kent.

Edgcote and Thame Valley are amongst more than 50 major viaducts being built as part of the HS2 project, which is designed to free up space on the most crowded part of the existing West Coast Main Line and boost economic growth.

The company’s civil engineers have designed the viaduct in a way that, instead of five beams per span secured with concrete poured on site, the twin viaducts use just two larger ‘u’ shaped beams per span, secured directly to the neighbouring beams.

This innovation - inspired by viaducts on the Spanish high speed rail network - will reduce the number of lorry movement 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 pre-cast concrete piers. These must be carefully lifted into position with their steel reinforcing rods slotted into pre-prepared sleeves within the pile caps. The gaps are then sealed with grout.

Suhel Uddin, HS2 Ltd’s Senior Project Manager, said:

“It’s great to see the first piers in place for Edgcote viaduct after our structural redesign. The success of the Thame Valley viaduct design shows that a two-beam approach can bring significant benefits for viaducts of this length – speeding up construction, boosting efficiency and improving safety on site by reducing the amount of working at height.”

As well as changes to the beams, the piers will also be narrower and extended to almost connect with the parapet edge, helping to enhance the appearance of a light and narrow structure. From a distance, it will be largely hidden by existing hedgerows and woodland.

HS2’s route has torn a huge scar through countryside on the eastern part of Banburyshire but the publicity office says two major new wildlife sites will be created where the viaduct crosses the floodplain, with new and enhanced fen, marshland and meadow alongside new woodland planting. ‘The schemes – which total 7.6 ha – will create valuable new habitats for insects, bats, newts and other amphibians’.

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 investigation has not found any evidence of the battle at the viaduct construction site, HS2 says.