What is a tunnel boring machine?

A tunnel boring machine breaks through ground material to remove it, forming a tunnel in the process with concrete segment rings.

 

At Hinkley Point C...

There will be three large tunnel boring machines and one smaller tunnelling kit that will be operating at Hinkley Point C.

The three largest machines will be forming the two intake tunnels, which will bring cold water from the Bristol Channel into the power station, and one outfall tunnel to send the water back. The other smaller kit will be excavating a tunnel to form the fish return system.

The first tunnel boring machine started its operation to construct the first of the intake tunnels September 2019 and will continue for 12 months.

How does the tunnel boring machine operate?

With its rotating cutting wheel at the front of the machine, the tunnel boring machine breaks materials away from the tunnel face. This earth is then transferred to the belt conveyor system inside the machine. There are a number of hydraulic arms which push the machine forward continually using the previous constructed concrete tunnel ring as its platform. 

 

What are concrete segment rings?

6,000 concrete segment rings will form the walls of the three tunnels. These are created with reinforced segments and grout injected to secure them in place. The segments are being constructed in a state of the art facility at Bristol Port Dock in Avonmouth and the facility will create between 70-100 rings per week (each ring made of 6-8 segments).

Learn more about how a tunnel boring machine operates and how the team will construct the tunnels using segment linings.

Learn more about the tunnel system that is being developed at Hinkley Point C and what happens to the tunnel boring machines when they conclude their journey.

Tunnel boring in numbers

12

tunnellers in each working shift

2

water intake tunnels

1

water outfall tunnel

900k

tonnes of earth will be excavated

1.8km

water outfall tunnel

3.5km

water intake tunnels

12

months to construct each tunnel

44

metre shaft excavated to form launch platform

Tunnel boring machine naming and tunnelling history

“Tradition states that the machines have to be officially named before they can start work – and, as the patron saint of miners and tunnellers is Saint Barbara, they are given female names” Gareth Taylor, Project Manager.

A competition was run across the county of Somerset with 215 primary schools invited to enter names of inspirational women of which the machines could be named.

Gareth said: “After much deliberation, our naming committee decided to name the equipment after several prominent women in history.”

The winners are:

Beatrice

Beatrice Shilling 1909 - 1990, was an engineer well regarded by the RAF. Born in Waterlooville she designed the RAE Restrictor (also known as the Tilly orifice) to prevent Merlin engines in Hurricane and Spitfire fighter jets cutting out during nosedives. Beatrice was awarded an OBE in 1947 for her work.

Beatrice was chosen by Cannington Church of England Primary School, Year 5 Beech Class.

Emmeline

Born in Bristol, Lady Emmeline Pethick-Lawrence was a women’s rights activist. Alongside her husband, Frederick Pethick-Lawrence, she fought tirelessly for the right to vote.

Emmeline was chosen by Stogursey Church of England Primary School, Year 5.

Mary

World-renowned fossil dealer, collector and palaeontologist, Mary Anning became known for important finds in Jurassic marine fossil beds in the cliffs along the English Channel. She was born and lived in Lyme Regis.

Mary was chosen by St Peter's Church of England First School in Williton.

Sarah

For the smaller tunnelling kit.

The kit will be called Sarah, after English inventor Sarah Guppy, who worked with Isambard Kingdom Brunel on the design of the Clifton Suspension Bridge.

Sarah was chosen by -Stogursey Church of England Primary School, Year 5.

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