Stanton Precast will supply more than 13,290 tunnel segments to form an aggregate length of four miles of tunnel.
The precast segments are being made at the company’s factory in Ilkeston, Derbyshire, and then sent by road to three locations in rural Buckinghamshire and Northamptonshire.
The concrete supplier has had to increase its workforce by around 50% to fulfil the contract. New production sheds, casting and storage areas are also being built at the factory to accommodate the new work.
The three sections of cut-and-cover tunnels are in Chipping Warden (1.5 miles) and Greatworth (1.6 miles) in Northamptonshire and Wendover (0.9 miles) in Buckinghamshire.
The tunnels are being built by excavating a cutting in the ground, forming a tunnel box from the precast concrete segments, and then covering it over with landscaping. HS2 Ltd describes them as ‘green tunnels’.
On-site tunnel assembly is due to begin in the village of Chipping Warden early next year. For the Chipping Warden tunnel, more than 5,020 individual tunnel segments will be produced by Stanton as part of the contract awarded by HS2’s multi-national works contractor EKFB – Eiffage, Kier, Ferrovial and BAM Nuttall. A French contractor, Matière, has been given a subcontract by EKFB to install the tunnel segments on site. Completion is expected in 2024.
Designed as a double arch, the tunnels will have two separate halves for southbound and northbound trains. Five different concrete precast segments will be slotted together to achieve the double arch – one central pier, two side walls and two roof slabs. Each one will be steel reinforced, with the largest weighing up to 43 tonnes.
EKFB director Peter Bimson said that using precast segments for the tunnel box was “a demonstrable feat”. He said: “This off-site manufacturing is the result of the collaboration between some exceptional teams, using international engineering expertise.”
Stanton Precast managing director Colin Richardson said his company had been targeting this contract for more than four years. It was “the culmination of a lot of hard work”, he said.
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