Faults were discovered in the giant precast segments used to construct the first tunnel in Chipping Warden, Northamptonshire

The same team of tunnel segment manufacturer Stanton Precast and  main contractor EKFB – Eiffage, Kier, Ferrovial Construction and BAM Nuttall – have now begun assembling the project’s longest tunnel around Greatworth in West Northamptonshire.

HS2 said: “Lessons learned during the construction of a similar green tunnel at Chipping Warden are being applied to the delivery of Greatworth.

“These include changes to quality control and the delivery and installation of the segments.”

Shorter green tunnels are also being built at Wendover in Buckinghamshire, Burton Green in Warwickshire and in the London Borough of Hillingdon.

The Greatworth cut-and-cover tunnel will be one-and-a-half miles long and made from more than 5,000 giant concrete segments.

HS2 Ltd’s Project Client Neil Winterburn, said: “Greatworth is one of five green tunnels between London and Birmingham designed to protect the natural environment and reduce disruption for local communities – and it’s great to see the first arches in position.”

EKFB’s Programme Director Emmanuel Rossignol, said: “The design and construction approach of this tunnel is unique to the UK, and there are many benefits associated with this methodology, including a reduction in our carbon footprint, but it’s not been without its challenges along the way.

“Our expert teams are to thank for their dedication as we continue to advance the construction programme across the Chipping Warden and Greatworth green tunnels.”

The tunnel will be built in sections, with construction of the main structure expected to take around two years.