The 5,940 sqm structure, near Brackley, is being built to provide a safe corridor for small animals to cross the tracks. 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.
The 2.5km cutting is being excavated between the Westbury and Turweston viaducts on the outskirts of Brackley to reduce noise for local residents. The giant concrete and steel lid is for the birds. And bunnies. And other wildlife.
It is one of 16 similar bridges on the HS2 project that are not necessary from a structural or operational perspective but represent the sort of gold plating that have pushed costs up so exorbitantly that the sections to the north of Birmingham have had to be scrapped, thus making a nonsense of the original business case. The south gets gold plated infrastructure while the north gets nothing.
Two weeks ago HS2 chair and (still) acting chief executive Sir Jon Thompson told the Rail Industry Association's annual conference that a similar wildlife protection structure near Calvert in Buckinghamshire had added £100m to project costs. There, a 1km-long curved shed will cover the tracks alongside Sheephouse Wood to prevent bats being disturbed by rail traffic.
On Turweston’s animal protection structure, the foundations are now complete and 36 steel beams are being lifted in by a 600-tonne crawler crane to support the 99-metre-wide structure.
The beams were manufactured in sections and assembled on site. They weigh up to 105 tonnes and are being lifted in pairs. They will support a concrete deck formed of pre-cast slabs that 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.
Cameron Thompson, HS2 Ltd’s head of delivery, said: “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 was designed by HS2’s main works contractor EKFB, a team made up of Eiffage, Kier, Ferrovial Construction and Bam Nuttall, working with its engineer design partner ASC (a joint venture between Arcadis Setec and Cowi) and specialist architect Moxon.
It is not all extravagance; there have been some savings. During the design stage, better than expected ground conditions allowed the engineers to eliminate 102 deep piles and opt for shallow foundations instead.
EKFB structures project manager Luis Prieto said: “It's exciting to witness the construction of the wildlife bridge at Turweston. This innovative 5,940-square-meter structure will carry a country lane and footpath across the HS2 railway, providing a safe corridor for small animals, insects, and birds.
“I am extremely proud of the work the team has done, particularly in optimising the design of the structure's foundations, which has enabled a substantial reduction in the scope of work. Additionally, improvements to the construction sequence have driven excellent progress to date”.
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