Humber estuary gas tunnel drilling work finishes
A tunnel under the Humber estuary due to carry up to a quarter of Britain's gas supplies has been completed.
The three-mile (4.9km) long tunnel will house a gas pipeline running between Goxhill in North Lincolnshire and Paull in East Yorkshire.
The work about 100ft (30m) beneath the river has taken 18 months to complete, National Grid said.
Eight large sections of pipe on rollers will be pushed by hydraulic thrust machines into the tunnel next year.
Work was completed on Tuesday and work will now begin to dismantle the tunnel-boring machine that is 500ft (160m) long.
The tunnel will carry a "vital pipeline which can provide up to a quarter of Britain's gas supplies", according to National Grid.
About 160,000 tonnes of material, mostly chalk, was excavated and is being used to restore a former quarry near Goxhill.
The current pipeline connecting Easington on the East Yorkshire coast where gas comes ashore to the national network needs replacing.
It is in a shallow trench on the riverbed and is at risk of being exposed.
Steve Ellison, for National Grid, said: "It's the first time a tunnel has been constructed beneath the River Humber and a fantastic achievement for everyone involved."
National Grid said when complete the pipeline would be the longest hydraulically inserted pipe in the world.