HS2 has begun assembling the half-kilometre long Edgcote viaduct, which 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.
Set low into the landscape of West Northamptonshire, the 515m-long viaduct will carry the new railway across the floodplain of the River Cherwell, south of Chipping Warden.
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.
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.
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 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 26th July 1469, during the Wars of the Roses, the battle is thought to have taken place on the nearby Danesmoor and archaeological investigation has not found any evidence of the battle at the viaduct construction site.
The design and construction is being led by HS2 Ltd’s main works contractor, EKFB - a team made up of Eiffage, Kier, Ferrovial Construction and BAM Nuttall. They are working with design partner, TYPSA, Construction Partner FC Civils Solutions and architects Moxon.
EKFB’s Senior Project Manager, Dalvier Chana, said:
“It’s great to see the benefits of the construction solution materialise on site. We were able to reduce the need for temporary works by opting for quality precast piers to support the infrastructure. In turn this has helped us to achieve time-related delivery savings. Thanks to the team for always striving to find the optimum approach and for working collaboratively to achieve this goal.”
FC Civils Solutions’ Deputy Project Director, Jonatan Gomez, said:
“As Construction partner of EKFB, FC Civils Solutions’ team are very proud to continue contributing to the success of HS2. The installation of the first pier of Edgcote viaduct represents a significant milestone for the team and the project. It is a clear example of investment into innovative, efficient and sustainable design solutions.
“Our experienced teams worked collaboratively, applying best practices learned from Thame Valley viaduct and will continue to implement these whilst working towards delivering the next phases of the project with the same level of excellence, safety and quality.”
The last few weeks have also seen significant progress at HS2’s other major viaducts, with the completion of the project’s first viaduct - at Highfurlong Brook in Northamptonshire – and the completion of deck assembly at the Colne Valley Viaduct, which has now become the longest railway bridge in the UK.
