Engineers working for the HS2 project have begun assembling a new green bridge at Turweston on the edge of Buckinghamshire and West Northants.
The 5,940sq/m structure, near Brackley, will carry a country lane and footpath across the new high-speed railway with space on either side to provide a safe corridor for small animals, insects and birds.
The bridge will be planted with hedgerows and vegetation to provide cover for wildlife crossing one of the longest and deepest cuttings on the new high-speed railway.
It is one of 16 similar bridges on the HS2 project
With the foundations now complete, engineers have begun the delicate task of lifting the 36 massive steel beams that will support the 99m wide structure.
The team used a 600-tonne crawler crane to lift the beams into position on top of the twin abutments.
The beams, which were manufactured in sections and assembled on site, weigh up to 105 tonnes and are being lifted in pairs. They will support a concrete deck formed of pre-cast slabs which will support 2,700 cubic metres of earth to complete the landscaping.
Once the main structure is complete, excavation will continue beneath the bridge to complete the cutting in which the track will be laid.
This cutting will stretch for 1.5 miles between the Westbury and Turweston viaducts on the outskirts of Brackley, helping to reduce noise and disruption for local residents.
Cameron Thompson, HS2’s head of delivery, said: “It’s great to see the first beams lifted into position at Turweston and I’d like to thank everyone involved. Once complete, this impressive structure will help keep communities connected, while protecting wildlife and biodiversity on either side of the railway.
“Green bridges are relatively rare in the UK so it’s fascinating to see this project come together and I look forward to seeing it progress over the coming years.”
The bridge – thought to be one of the largest in the UK - was designed by HS2’s main works contractor EKFB, a team made up of Eiffage, Kier, Ferrovial Construction and BAM Nuttall, working with its design partner, ASC (a joint venture between Arcadis Setec and COWI) and specialist architects Moxon.
During the design stage, better than expected ground conditions combined with design optimisation, allowed the team to cut the structure’s carbon footprint by 42%.
This was achieved by significantly reducing the amount of carbon-intensive concrete and steel by removing 102 deep piles and opting for shallow foundations instead.