‘Mary’ completes epic journey

‘Mary’ the tunnel boring machine completes epic journey under the River Humber

• National Grid and project partners achieve major feat of engineering tunnelling under the River Humber.

• Tunnel boring machine ‘Mary’ completes her journey connecting Goxhill on the south bank to Paull on the north bank of the river.

• Project now preparing for world record-breaking pipeline push through the tunnel early next year.

‘Mary’ our 160-metre long tunnel boring machine digging the tunnel to house a replacement gas pipeline 30 metres beneath the River Humber, completed her epic journey on Tuesday 10th September, 2019 at 12.08pm. Watch the final ring installation here

The breakthrough, into the specially constructed shaft at Paull on the north bank of the river, marks the end of her 18-month journey from Goxhill on the south side and the start of the next phase of this world record breaking feat of engineering.

The tunnel distance of nearly 5km and a 3.65 metre diameter tunnel will carry a vital pipeline which can provide up to a quarter of Britain’s gas supplies.

During her journey under the Humber, ‘Mary’, the size of approximately 11 double decker buses in length, has excavated approximately 160,000 tonnes of material – mostly chalk, which has been carefully transported back to the surface, graded and re-processed at the Goxhill slurry treatment plant. The excavated material is being used to help restore a former quarry nearby.


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.”

In Spring 2020, two hydraulic thrust machines will start the epic task of carefully pushing 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.

When one pipe section has been installed, the next will be moved into position, welded to the one in front, and the push will continue until all five kilometres of pipeline is installed beneath the river. When complete it will be the longest hydraulically inserted pipe in the world – a truly incredible feat of engineering for National Grid and its project partners!

Watch a Modelled fly through of the Humber River pipeline tunnel here.