The Channel Tunnel – A Modern Engineering Wonder of the World

May 11, 2022 | Articles, Technology

There have been many engineering marvels over the course of history. Each of them is grand and spectacular in its own way. Today, we will talk about an engineering wonder that connects United Kingdom and Europe. Called the Channel Tunnel, it is an underwater rail tunnel that runs beneath the English Channel.
This tunnel, called also the Chunnel, connects Folkestone, Kent in the United Kingdom and Coquelles, Pas-de-Calais in France.
It officially opened on May 6, 1994. But it was a centuries-long idea. The engineering feat is an impressive piece of infrastructure. Over the years, more than 13,000 workers were hired to finish off the construction.
The Queen and President Mitterrand officially opened the tunnel when the royal party traveled from Waterloo to Calais at a sedate 80mph.


As we said before, the Chunnel was officially opened in 1994. That project was built thanks to the revived idea in 1986 by the UK and France. They choose a rail tunnel over proposals for a very long suspension bridge, or ideas like a bridge-and-tunnel link.

The project was financed by a consortium of British and French corporations and banks. Digging started in 1987-88 and was completed in 1991.
But this is not an idea that came up lately. In fact, it is a centuries-long idea. The first time it was proposed was in 1802, when Albert Mathieu-Favier, a French mining engineer, proposed to tunnel under the English Channel using illumination from oil lamps.
His design envisioned a bored two-level tunnel with the top tunnel used for transport, while the bottom for groundwater flows.
Then, in 1839, Aime Thome de Gamond, a Frenchman, performed the first geological and hydrographical survey, exploring several schemes. He was the one who proposed to Napoleon III a mined railway tunnel from Cap Gris-Nez to East Wear Point. At the time, the project was worth 170 million francs, or less than 7 million British pounds.
There was another proposal in 1929, but nothing came of it. At the time, the proposal put a construction price of $150 million. In this proposal, engineers addressed the concerns of both nations by designing two sumps, one near the coast of each country. Each of them could be flooded at will and block the tunnel. This did not appease military leaders.
Fears continued during World War II. Because France fell, British calculated that Hitler could use slave labor to build channel tunnels in 18 months. And they speculated that Germany had already begun digging.
Yet, no tunnel was built up until the 1980s.

Key Dates

– Albert Mathieu puts forward the first cross-Channel tunnel proposal in 1802
– In 1875, the Channel Tunnel Company Ltd began preliminary trails
– In 1882, the Abbot’s Cliff heading had reached 897 yards
– The UK-France government-backed scheme that started in 1974 was canceled in January 1975
– France and Britain signed the Treaty of Canterbury in February 1986, opening the way for the project to proceed
– In 1988, tunneling commenced in France
– In December 1990, service tunnel broke through under the Channel
– Queen Elizabeth II and President Mitterrand formally opened the tunnel in May 1994
– By June 1994, freight trains commenced operations
– In November 1994, passenger trains commenced operations
– In November 2007, High Speed 1, linking London to the tunnel, opened
– In November 2011, the first commercial freight service run on High Speed 1

Dimensions of the Chunnel

Official documents state that the Channel Tunnel is 31.35 miles long, 24 of which are located underwater. This makes the tunnel the 11th longest in use, and fifth longed used by rail passengers. At the same time, it has the longest undersea portion of any tunnel in the world at 23.5 miles. For comparison, the longest tunnel is Paijanne Water Tunnel in Finland at 74.6 miles.
You can say that the total tunnel length is longer. There are three tunnels that travel from Great Britain to France, and many small ones that connect the main ones. Total tunnel length is 95 miles worth of tunnel.


The initial cost of construction was estimated at $3.6 billion, but it came way over budget. When finished, it cost more than $15 billion.

At the height of construction, more than 13,000 people were employed. Over the years, ten workers have died building the tunnel. Eight of them were British.
For digging, companies used 11 boring machines, with a total weight of 12,000 tonnes, which is more than the Eiffel tower. Each of these machines was as long as two football pitches.

The Spoil

Spoil is the name people used for the chunks of chalk removed by the TBMs while digging the Chunnel. There were millions of cubic feet of chalk. So, a place had to be found to deposit all of it.
The British decided to dump their portion into the sea. Yet, they were careful not to pollute the English Channel with chalk sediment. So, they made a gigantic sea wall of sheet metal to keep the debris contained.
The chalk piled higher than sea level, creating the land that we now call Samphire Hoe, a total of 73 acres seeded with wildflowers. It now serves as a recreation site.
The French were able to dump the spoil nearby, creating a new hill that was later landscaped.

Immigration concerns

Both the British and French have been concerns about illegal immigration over the years. Illegal immigrants have used the tunnel to attempt to enter Britain since its opening. And by 1997, it attracted international press attention.
In 1999, the French Red Cross opened the first migrant center at Sasngatte. Most illegal immigrants are asylum-seekers. They usually find a way to ride a freight train. There have been cases of immigrants stowed away in a liquid chocolate tanker that managed to survive.
In 2001 and 2002, riots broke out at Sangatte, and immigrants stormed the fences and attempted to enter en masse.


When you talk about traveling through the Chunnel, up to 400 trains pass through each day. They carry on average of 50,000 passengers, 6,000 cars, and 54,000t of freight.

These trains take on average of 35 minutes to travel the length of the Channel tunnel.
Since the introduction of a pet travel scheme in 2000, more than one million dogs and cats have travelled through.
Nowadays, the Chunnel is recognized by the American Society of Civil Engineers as one of the Seven Wonders of the Modern World, alongside the Empire State Building, the Itaipu Dam in South America, the CN Tower in Toronto, the Panama Canal, the North Sea protection works in the Netherlands, and the Golden Gate Bridge in San Francisco.

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Thomas B.