Where does this come from, and can I check it?

In December 1990 the British and French borings joined within a few centimetres of the planned line. The figure is taken from Britannica, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.

Is this really a technology fact?

Yes. It sits on the Technology shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.

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The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.

Mondo Knows Facts

Two tunnel machines met under the Channel

In December 1990 the British and French borings joined within a few centimetres of the planned line Surveyors guided each machine by laser and gyroscope, checking the position against the surface through a shaft every few hundred metres. The service tunnel broke through first, and the machines were then steered into each other's path to meet. The completed link runs 50 kilometres, with 38 of them beneath the seabed. It sits in Mondo's technology collection, one of 200 facts that each trace back to the reference below.

Where this comes from

Britannica

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Tags: tunnels, surveying, engineering

Two tunnel machines met under the Channel: the short answers

Where does this come from, and can I check it?: In December 1990 the British and French borings joined within a few centimetres of the planned line. The figure is taken from Britannica, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.
Is this really a technology fact?: Yes. It sits on the Technology shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.
What else can I read about it?: The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.