National Grid has announced its 160-metre long tunnel boring machine has successfully completed an almost 5km tunnel underneath the River Humber.
The 4.86km tunnel from Goxhill on the south side of the river to Paull on the north bank took 18 months to complete.
Workers are now preparing to push through a pipeline which can provide up to a quarter of Britain’s gas supplies.
The boring machine, named ‘Mary’, is the size of approximately 11 double decker buses in length and has excavated approximately 160,000 tonnes of material.
Steve Ellison, lead project manager, capital delivery, for National Grid, said: “Completing the tunnel beneath the Humber is a major milestone for the project team and our project partners.
“It’s the first time a tunnel has been constructed beneath the River Humber and a fantastic achievement for everyone involved.
“Over the next few weeks we’ll be dismantling the tunnel boring machine and lifting her out of the ground in sections, ready to be transported back to Germany, where as much as possible will be refurbished and renewed to get her ready for her next tunnelling job.
“The next steps for us here under the Humber involve clearing the pipes, cables and ancillary equipment that has been servicing the tunnel boring machine and preparing for the world record breaking pipeline installation early next year.”
The next stage of the process will see two hydraulic thrust machines push eight huge 610-metre long and 850 tonne sections of pipe on rollers into the new tunnel from the Goxhill side.
The pipes will be pushed at about one metre per minute into the tunnel which will have been flooded with water to aid installation.