Year
1994Duration
6 yearsCost
£4.65bn (£12bn today)Location
United Kingdom and FranceProject achievements
Connected communities
Physically connects the UK with the European continent
Economy boosted
Much quicker, easier way of transporting freight and people
Solved the problem
Significantly cut travel time between the UK and the continent
Connect the UK to continental Europe with an undersea tunnel
The Channel Tunnel — also known as the 'Chunnel' — is the longest undersea tunnel in the world at 50.45km (31.5mi) long. Of those, 37.9km (23.5mi) are under the English Channel.
It was opened in May 1994 by Queen Elizabeth II and French President François Mitterrand. It took six years to build.
After travelling through the tunnel, the Queen said it was one of the world's greatest technological achievements.
The Channel Tunnel is really three tunnels, running parallel to each other. Trains go through two larger tunnels, one running south from the UK to France, and one going north, from France to the UK.
A smaller service tunnel – used for ventilation and access - runs between the two train tunnels.
The tunnels don't run straight - they curve gently up and down or left and right. This is so they can run through the chalk strata. On average, the tunnels are 45m below the sea bed.
The two larger tunnels are 7.6m wide. They're high enough to take a double-decker bus.
The larger tunnels merge at two points under the sea called 'crossovers', where the trains change line. These crossovers are undersea caverns and they're as wide and long as a cathedral.
The UK and France are about 21 miles apart at their nearest point. However, the three tunnels are 35 miles long as they run to terminals inland at Folkestone and Calais.
The American Society of Civil Engineers elected the Channel Tunnel one of the seven modern wonders of the world in 1994.
"Every generation has to do something exciting that will affect the future. This is wonderful, even better than I thought it would turn out.”
Margaret Thatcher, the UK Prime Minister who gave the project the go-ahead
Did you know …
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The first serious proposal for a Channel tunnel came from French engineer Albert Mathieu in 1802. It included an artificial island half way across for changing horses.
- The Channel Tunnel was picked over proposals to build a very long suspension bridge, 38.6km (24mi) to be exact.
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Eleven tunnel boring machines (TBMs) were used on the project. One of the TBMs from the British side is now buried under the Channel. Another sold on eBay for £39,999 in 2004.
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Each year, the tunnel carries on average 10 million passengers on Le Shuttle, 11 million passengers via Eurostar and four million dogs.
- Queen Elizabeth II was the first official passenger to travel through the Channel Tunnel – but her train was delayed seven minutes due to signalling issues.
Difference the Chunnel has made
The first Eurostar service started running in November 1994.
Since then, the Channel Tunnel has cut travel times between the UK and mainland Europe dramatically.
Before the tunnel, it took around six or seven hours by rail and ferry from London to Paris. Trains can now do the same journey in 2.5 hours.
It's also possible to cross the Chunnel by car, using the Le Shuttle service.
At first there were fears that the Channel Tunnel would fail, as it had to compete with cheap airlines.
But the tunnel has become an essential infrastructure asset for tourist, business and freight transportation. It allows fast travel in all weathers.
How the tunnels were dug
Digging started in 1988, with tunnel boring machines (TBMs) used for all the tunnels. Five TBMs dug from France, six TBMs dug from the UK.
The TBMs started work on the service tunnel first. This was so engineers could see what the actual ground conditions were like.
The two crossover caverns were built using access from the service tunnels. TBMs digging the main tunnels passed through the caverns and then plunged back into the chalk to carry on digging.
Ground conditions at the French end were wetter than at the British end. This meant the French machines moved more slowly and that British TBMs dug more of the tunnels.
Engineers used two systems of tunnel linings – cast iron segments bolted together and precast concrete rings.
The TBMs excavated a huge amount of chalk.
On the French side, the chalk was crushed, mixed with water, and pumped inland behind a specially built dam 37m high.
On the British side, engineers used the chalk to build a landscaped platform at the foot of Shakespeare Cliffs near Dover.
A French TBM and a British probe met under the sea for the first time in October 1990. Their alignment was pretty spot on – it only varied by 358mm horizontally and 58mm vertically.
People who made it happen
- Anglo-French consortium Transmarche Link (TML) built the tunnel. TML was made up of companies from the UK and France.
- UK companies: Balfour Beatty, Costain, Tarmac, Taylor Woodrow, Wimpey.
- French companies: Bouygues, Dumez, SAE, SGE, Spie Batignolles.
