The engineering marvel of shield tunneling: the fascinating history of the English Channel Tunnel

The English Channel Tunnel as envisioned in the 1950s. © The Telegraph

Leviathan Press:

Building an undersea tunnel between Britain and France is a huge engineering challenge, and before this, there was only the Seikan Tunnel in Japan as a precedent. One of the serious threats faced by undersea tunnels is that under fragile geological conditions, the seawater above will rush in due to water pressure. Looking back at history, undersea tunnels are not just a simple engineering miracle, but also related to the complex emotions and attitudes of the United Kingdom towards the European continent.

The English Channel (called la Manche in French, meaning "the sleeve" to the French) is one of the most rugged sea routes in the world. At its narrowest point, the Strait of Dover, it is only 20 miles (about 32 kilometers), but this distance is not much comfort to those who attempt to cross it. The shallowness of the channel, combined with its unique tides, currents and permanent fog, makes navigation treacherous and seasickness is notorious.

For centuries, the English Channel served as Britain’s defense against foreign invasion. Bad weather was divinely explained as the “Protestant Wind” that sank the Spanish Armada in 1588. But it was also a double-edged sword: merchant ships were just as vulnerable as Philip II’s massive fleet. The advent of the Industrial Age brought peace and trade, and by the early 19th century, Britain had become the world’s largest producer of manufactured goods. Improvements in shipping and port facilities greatly facilitated trade, but the logistical problem of transferring goods from ship to shore remained. Faced with this problem, people began to consider ways to avoid the waterway altogether.

Jean-Pierre Blanchard made the first hot air balloon crossing of the English Channel on January 7, 1785. © Media Storehouse

The first balloon crossing of the English Channel took place in 1785, but the first airplane didn't fly across the channel until 1909. In 1851, a telegraph line directly connected London and Paris. Could railways be possible? Many engineers thought so: they proposed a tunnel plan to connect Britain's roads and railways to the European continent.

This was not simply a question of engineering and geology, however. The idea of ​​a fixed connection was closely tied to the British understanding of international relations and their place in Europe in the age of imperialism. On one side were the liberals who believed in a common Europe, founded on a belief in the unity of the “peoples” and in international communications and free trade. For these progressive advocates, the great railway projects represented the spirit of the times: as one supporter put it, the rails “joined the hearts of the nations together”.

Engraving by an unknown artist showing Napoleon's invasion of Britain by air, sea and undersea tunnel, 1803. © meisterdrucke

Opposing this approach were the more pessimistic and suspicious British, who saw Europe as permanently divided by diplomatic, military and imperial tensions. To them, the railway was a weapon and the proposed Channel Tunnel a military front that would expose their wealthy but unprepared island to the armies of continental Europe.

It was this clash of world views, rather than engineering challenges, that determined the project's fate.

French pioneer

In 1802, during a lull in the Napoleonic Wars, a French mining engineer named Albert Mathieu proposed what is believed to be the first plan to cross the English Channel. He envisioned a tunnel ventilated by huge iron chimneys that would protrude out to sea, an artificial "international island" on Varne Bank at the midpoint of the channel, relay stations so that carriages could change horses, and ports.

Albert Mathieu's plan for a horse-drawn coach service across the English Channel, circa 1802. © wikipedia

The plan was prominently exhibited at the French School of Mines and the legislature, where Napoleon Bonaparte may have seen it for the first time. It also attracted the attention of British opposition politician Charles James Fox, who reportedly responded enthusiastically. However, with the return of the war, the project was shelved.

Thirty years later, Mathieu’s legacy was inherited by Aimé Thomé de Gamond, who is best known as the “Father of the Channel Tunnel.” A 19th-century Renaissance man, de Gamond earned doctorates in medicine and law in addition to his studies in geology and engineering. While studying the rivers of France, de Gamond became intrigued by the idea of ​​a cross-Channel connection. By the late 1830s, he had drawn up plans for everything from a massive bridge to an iron tube to a masonry tunnel under the sea.

Illustration of the Anglo-French underwater tunnel designed by Thomé de Garmon for the 1867 World's Fair. The yellow circle in the upper left corner represents a large spiral ramp that would allow access to the tunnel from the international artificial island on Varne Shoal. © wikipedia

De Garmont was not the only one who aspired to connect Britain to the European continent. However, due to their lack of geological knowledge, few of his peers dared to propose building tunnels under the sea.

While studies have shown that geological layers are the same on the English and French coasts, it is unclear whether the Strait of Dover itself is a rift valley that separated the two coasts, or the erosion of an ancient land bridge that once connected Kent to northern France. If the strait is a rift valley, then tunneling would be difficult if not impossible - any attempt would involve tunnelling through unknown and inconsistent geology that could contain solid rock, requiring extensive manual labour or the expense of blasting.

Illustration of Hector Horeau's (one of Thomas de Garmont's early tunnel dreamers) Anglo-French proposal for a tubular submarine railway. © archive

After exhausting all land-based research methods, Tomé de Garmon made three extraordinary solo dives in 1855 to solve the mystery of the channel. He carried 160 pounds of flint, plugged his ears with homemade lard plugs, and turned his mouth into a de facto valve - using olive oil to expel air instead of taking in water. With these equipment, he successfully dived more than 100 feet (about 30 meters) to sample the seafloor, and then surfaced with the help of a dozen inflated pig bladders. On the last dive, he found himself having to fend off an attack from a giant eel.

Tomé de Garmon dived alone to explore the English Channel. © wikipedia

The venture was a success. Examination of the samples confirmed that Britain and France had once been connected by a landmass that had since eroded away, and that the geological layers between the two shores were continuous. Because the rock was soft chalk, the work would not require the time-consuming and laborious drilling and blasting. For the first time, the plan to drill a tunnel became feasible.

Zeitgeist

Thome’s discovery came at a fertile moment in the history of European thought and science. Europe’s rapidly expanding technological, industrial and economic power, and the imperialist hubris that resulted from it, gave rise to an intoxicating cult of scientific progress where anything seemed possible. Railways were at the forefront of this new world. The first commercial railway between Liverpool and Manchester opened in 1830, and by 1850 more than 20,000 km of track stretched across Europe.

Engraving of a train journey from Liverpool to Manchester, 1831. © Science and Industry Museum

Tunnels have been an integral part of railway construction since the beginning, but in the second half of the 19th century, tunnel construction took off on a grander scale, with the opening of the Mont Cenis Tunnel through the Alps connecting France and Italy in 1871, followed by the opening of the 9-mile (14.5-kilometer) Gotthard Tunnel in 1882, the longest tunnel in the world at the time.

The northern entrance to the Gotthard railway tunnel in the Swiss town of Göschenen, circa 1880. © wikipedia

Four years later, a four-mile tunnel under the Severn Estuary connected England and Wales. These feats of engineering, writes the technology historian Rosalind Williams, “embodied progress as understood by the age.” The completion of each line was seen as a triumph of science over nature, its designers and builders as pioneers of a civilization’s steady march forward.

In this context, the lack of an English Channel link was not only an anomaly but also a failure of economic and social progress. As engineer and tunnel advocate James Chalmers wrote in 1861:

Looking down on a European railway map, the discerning eye can trace many lines leading to a particular point, almost always to a major city. There is one notable exception, however: across continental Europe, from the north, east and south, and in England from the south, west and north, the lines can be seen converging, their arms outstretched as if to embrace, and yet... they stop.

Title page illustration of James Chalmers's 'Channel Railway', from his The Channel Railway Connecting England & France (1861). © wikimedia

Enthusiasm for technological progress went hand in hand with the rise of liberal internationalism, embodied in events such as the London World’s Fair of 1851 and the Anglo-French Free Trade Treaty of 1860. The treaty’s principal drafters, Richard Cobden and Michel Chevalier, taught that the forces of history were moving inevitably toward human solidarity: improved trade and communications would eventually make war obsolete.

They idealized "the people" and attacked "vested interests" in the armed forces and the aristocracy as the real drivers of international conflict. "Free trade is God's diplomacy," Cobden once wrote, "there is no other way to ensure the peaceful coexistence of men." Cobden and Chevalier both supported the Channel Tunnel project as an important step towards the eventual unification of Europe and "the true arch of union," a phrase often quoted by Cobden and often used by tunnel advocates.

De Garmont's efforts bore fruit in 1856 when he presented a comprehensive plan for a double-track railway tunnel connecting East Wear Bay near Folkestone to Cap Gris-Nez in the Pas-de-Calais.

Like Mathieu, he envisioned an international port on the Varne Sandbanks, with ventilation shafts and lighthouses along the way. Construction would begin on temporary stone islands built at intervals across the English Channel, from which ventilation shafts would be sunk, while the tunnel would use the steel "shield" pioneered in the construction of the Thames Tunnel.

Map showing Thomas de Garmont's preliminary design for a tunnel linking England and France, 1857. © wikimedia

Praised by leading engineers such as Robert Stephenson and Isambard Kingdom Brunel, and supported by Queen Victoria, Prince Albert and Napoleon III, the scheme seemed to be on its way to achieving what, according to its inventor, would be a “useful and glorious end”.

Design of a tunnel linking Folkestone, England, and Cap Griet, France. © wikimedia

However, in a sequence of events that would be all too familiar to tunnel supporters, the project collapsed as relations between the two countries frayed. After an Italian nationalist attempted to assassinate Napoleon with a British-made bomb, the British press whipped up an invasion scare. Prime Minister Lord Palmerston, who hated France, took advantage of the situation and surrounded Plymouth and Portsmouth with expensive and useless fortifications.

In contrast to the optimistic liberals, Palmerston believed that the tunnel would remove ‘our natural defences against continental enemies.’ Cobden and Chevalier believed he was obsessed with the Napoleonic wars of his youth: ‘His mind was full of thoughts of a French invasion.’ This was the pessimistic and suspicious worldview that the tunnel advocates had to overcome if they were to succeed.

UK-led

In the 1860s, British engineers such as William Low and John Hawkshaw joined Tomé de Garmont in abandoning the Vane Bank idea and focusing instead on the sea between Dover and Calais. After extensive soundings and surveys, by the end of the 19th century a joint Anglo-French committee was established to advance the project.

In 1872, the British Channel Tunnel Company was formed, and in 1875 the French company followed. At the suggestion of the British (Palmerson was replaced as Prime Minister by the more sympathetic Disraeli), representatives of the two countries formed a formal joint committee to draw up specifications and regulations for the proposed tunnel. On August 2, 1875, both countries passed acts authorizing their respective companies to begin construction.

Less than two years later, however, progress had stalled. The continued lack of complete proof of viability undermined investor confidence. Plagued by financial problems, the British company had made little substantial progress by 1876, and the charter granted by the 1875 Act expired.

"Geological Map of the Straits of Dover, Showing the Probable Line of Outcrops Across the English Channel", from William Topley, The Geology of the Straits of Dover, The Quarterly Journal of Science (1872). © archive

It was at this time that the tunnel was taken over by Sir Edward William Watkin, the independent Liberal MP for Hythe and chairman of three major railway companies, including the Southeastern Railway, which operated in Kent. Watkin was combative and stubborn, a consummate businessman and publicist, fascinated by large and visionary engineering projects and passionate about free trade.

He assembled a prestigious scientific and legal advisory committee that included lawyers, electrical, hydraulic and mining engineers, geologists, military personnel and the president of the Royal Society, but the key figures were two Royal Engineer officers, Colonel Frederick Beaumont and Captain Thomas English, who ultimately proved the feasibility of the tunnel project.

Both men were skilled inventors. In the late 1870s, Beaumont was experimenting with locomotives and streetcars powered by compressed air. English was an expert in steel armor plates (the material needed to make durable mining equipment), and in 1880 he patented a new boring machine based on Beaumont’s previous design. A year later, the two used English’s patent to produce a tunnel boring machine, powered by Beaumont’s compressed air engine. It turned out to be the perfect tool for the job.

Colonel Beaumont's design for an air locomotive, capable of pulling a 150-ton train through the tunnel on a single charge, illustration from Charles Tylden-Wright's paper "The Channel Tunnel", published in Volume XXXII of the Northern Institute of Mining and Mechanical Engineers (1882-1883). © archive

A cross-section of the seabed of the present course of the Strait of Dover, showing an isometric perspective of Colonel Beaumont and Captain English's air-compressed boring machine, from an illustration to Arnold Lupton's paper on 'The Channel Tunnel', published in the Proceedings of the Yorkshire Geological and Technological Society, Volume III (1883). © archive

Equipped with a rotating cutter that digs a 7ft diameter tunnel at a rate of one yard per hour and a conveyor belt for removing the dirt, the machine requires fewer than 10 workers to operate. Crucially, its electric power means that not only does it not produce dangerous exhaust fumes, but it also releases air as it works to ventilate the tunnel.

On October 14, 1880, the Beaumont-English tunnel boring machine began drilling test tunnels at Abbots cliff near Dover. The machine was able to cut easily through the grey chalk rock, which was almost impermeable. After digging 842 yards (about 770 meters) of tunnel test tunnels, the machine was moved to a new site under Shakespeare cliff in September of the following year, the closest point between England and France.

A Beaumont-English roadheader working in soft rock. © archive

At the end of the year, Watkin formed the Submarine Continental Railway Company to oversee the work. France's Compagnie du Chemin-de-fer Sousmarine soon began working from Sangatte, near Calais, using a modified Beaumont-English roadheader. For the first time in the project's history, miners were working on the seafloor.

Copperplate engraving of the underwater tunnel project between France and England by Frederic de Haenen, circa 1850-1900. © meisterdrucke

Beaumont declared, “It will be one of the proudest moments of my life to see that the dream I have always dreamed of could be realized.” But Beaumont had bigger dreams. He envisioned an international undersea railway powered entirely by compressed air, with carriages pulled by 80-ton locomotives that would ventilate the tunnels as they traveled.

Digging towards disaster

In June 1881, Watkin announced to a surprised nation that he expected to have a preliminary “experimental” tunnel completed within five years, with the line scheduled to open in the 1890s. “I am an islander by birth, but my ambition is to become a member of the great continent,” he said. The only obvious obstacle was getting an Act of Parliament passed to allow the company to tunnel under the seabed, on state-owned land.

The Channel Tunnel would be the crowning achievement of international engineering and of Watkin's own career, "a work unrivalled in all labour yet accomplished by human hands." It would be both a practical continuation of Richard Cobden's work and a concrete step towards the eventual European Free Trade Association. By establishing economic and personal links between the British and French populations, the tunnel would help to dispel mutual hostility, allowing new understandings to "permeate the masses of both countries." Watkin said: "It is evident that every year the English Channel becomes more impassable, and an obstacle to intercourse between nations."

Design of Colonel Beaumont and Captain English's compressed air boring machine in the 1890s. © meisterdrucke

Watkin’s vision of European unity was uniquely British. A committed patriot and internationalist, he firmly believed that free trade and peace were the keys to Britain’s economic and imperial success. The Channel Tunnel was a way to export these values ​​to the continent:

“…the Continent will benefit from better and closer contact with the liberties and industries of England…friendly competition in all trades and professions will become a common heritage for the benefit of the whole world.”

This passion for the “advancement” of science, commerce, and civilization was most powerfully expressed in Parliament by Lord Brabourne, Watkin’s representative:

"Despite all opposition, science is always progressing; on current issues, civilization and Christian culture are moving forward hand in hand; the obstacles caused by isolated prejudices and the empty talk of professional pedants may last for a while, but they will eventually become pale and powerless in the face of the spirit of the times. With the victory of the English Channel Tunnel, the hearts of peoples of all countries will be more united and closer to a full and happy recognition of the universal brotherhood of mankind!"

By January 1882, it seemed that there was no obstacle to Watkin’s Channel Tunnel. Public opinion was in favor, and the Liberal government, led by Watkin’s friend William Gladstone, was also a supporter of the tunnel. Gladstone had won the 1880 election on a platform of internationalism, peace, and free trade; for Watkin, the Channel Tunnel was the ideal embodiment of these policies.

John Tenniel's illustration for an 1865 issue of Punch magazine, titled "The Water Babies", shows Mrs. Britain saying to Mrs. France: "It is delightful, isn't it, my dear, to see the children become such good friends?" © wikimedia

However, at this moment, the power that had been suppressed suddenly erupted.

Unknown to the public, an official committee of the Board of Trade, the War Office and the Admiralty was set up in 1881 to examine the implications of a tunnel under the sea. One of their pieces of evidence was a memorandum from Sir Garnet Wolseley, the Lord Provost of the Army.

Although publicly an efficient professional soldier, Wolseley was politically a profound reactionary who openly despised the liberal worldview of Cobden, Gladstone and Watkin. Wolseley's memorandum on the tunnel was not a careful technical document but a blistering attack on the "false universal brotherhood" and "selfish cosmopolitans". In place of Watkin's optimistic predictions of Anglo-French rapprochement, Wolseley replaced it with his own analysis of relations between nations, emphasising the inherently violent and envious nature of human beings.

A chronic pessimist, Wolseley believed that Britain’s military was woefully underfunded, a situation he laid squarely at the feet of liberal internationalists. “We have lived in a state of unpreparedness for war, owing to our confidence in the good will of others,” he wrote. In this context, liberal, wealthy Britain was a trophy to be seized, not a civilization to be emulated. An undersea tunnel, he argued, would “constantly tempt the unscrupulous foreigner to make war on us, because it would give him hopes of conquest never before imagined.”

Wolseley noted that in recent wars in the United States and Europe, the use of trains had enabled generals to move troops farther and faster than ever before. Connecting Britain to France would expose Britain to the same dangers. He noted, without evidence, that the tunnel could carry 5,000 soldiers an hour into the country. He envisioned a sudden attack during a time of “deep peace,” with no warning and no formal declaration of war, “while we gentlemen of England are in our beds, dreaming of the time when the lion and the lamb shared a dream.”

Since London was the only undefended capital in Europe and had no large-scale conscription army to compete with France or Germany, Britain would quickly be defeated and incorporated into continental Europe, facing "national extinction" and becoming "eternal French helots (Editor's note: the helot system was a state-owned slave system in the ancient Greek city-state of Sparta)."

"The Lion Cannot Face the Cock's Crow", illustration by Friedrich Graetz for Punch magazine, July 1883, showing Wolseley riding a lion to flee from the French cock. The illustration was published the day after Watkin's English Tunnel (Pilot Works) Bill was withdrawn from Parliament. The inscription on the tunnel reads: "The English Tunnel Monster". © wikimedia

The real sharpness of Wolseley’s argument lies not in his vision of future war scenarios, but in his analysis of British society. Individual freedom, low taxes, free trade and a small army are possible because the English Channel provides security. The introduction of a tunnel, however, would fundamentally shake this consensus. It would cause the country to fall into a “panic”, a terrible state that all countries with insignificant armies and very powerful neighbors experience periodically.

Any action by the French army near Calais could trigger panic in the UK about an imminent attack. Without the ability to develop an absolutely secure defense system, the UK would be trapped in a series of escalating panics and huge military spending plans. The result is that the UK will eventually have to "follow the example of European countries" and establish a comprehensive military service system.

Furthermore, Wolseley asserted that he believed such an army was impossible under "our system of government", suggesting that an undersea tunnel might do away with parliamentary democracy itself. The greatest threat posed by the tunnel, therefore, was not necessarily the terror of invasion but the economic and social costs of countering such a threat.

Panic Petitions and Undersea Champagne

In February 1882, Wolseley's memorandum was published in The Nineteenth Century, and the following month he and other army and naval officers began a concerted public campaign against the tunnel. In this they were helped by the editor of The Nineteenth Century, James Knowles, who organised a special issue and a petition against the plan signed by a number of prominent (if not entirely representative) public figures, including many prominent liberals such as Thomas Henry Huxley, Herbert Spencer, and 14 Liberal MPs.

Knowles’s accompanying paper boiled down Wolseley’s arguments to three major fears: the “inevitability” of increased military spending, the “possibility” of panic, and the “probability of irreparable catastrophe.” Clearly, these issues struck a deep nerve in liberal Britain. At a crucial moment, many did not trust that “the people” would embrace their connection with the New World in a spirit of universal brotherhood. “The alarmists signed the petition because they were alarmists,” wrote The Scotsman. “The non-alarmists signed because they did not wish the country to be disturbed.”

"Lord Watkins's Remedy for the Invasion Panic: Drown the French in the Channel Tunnel", double-page illustration from The Penny Illustrated, 1881. © printsandephemera

Watkin responded to these attacks with every means at his disposal. He encouraged his friends to speak out in favor of the tunnel, and soon newspapers and journals were abuzz with debate over the plan. He had particular success with a powerful article by Sir Andrew Clarke, the Commandant of the Royal School of Military Engineering. The article assured readers that there was no historical precedent for deploying an entire army along a single railway line, and dismissed the possibility of a covert invasion as "pure impossibility."

More generally, tunnel supporters pointed out that it would be very easy to destroy, block or flood the tunnel, especially since the entrance was under fire from the guns of Dover Castle and any warships anchored in the port. Watkin also used softer means of persuasion, inviting various celebrities (including Gladstone and Wolseley) to visit the tunnel project on the seabed, where they could enjoy champagne receptions under electric lights and inspect the boring machines.

Illustration of a champagne reception at the Channel Tunnel, from The Illustrated London News, 1882. © wikimedia

These rebuttals failed to stem the tide of public opinion, which, in a panic, turned strongly against the tunnel. Torn between personal beliefs and political instincts, Gladstone referred the issue to a parliamentary select committee, but the committee failed to reach a unanimous decision, voting six to four against the plan. This was the excuse the government needed to get out of its predicament. Watkin's Channel Tunnel (Experimental Works) Bill was formally withdrawn from the House of Commons on 24 July 1883.

Work on the title Shakespeare Cliff had ceased in August 1882; the Board of Trade was eventually forced to issue an injunction against Watkin, who at one point declared a willingness to go to jail over the tunnel. When Sangat's machine was shut down on 18 March 1883, the two companies had dug 3,863 yards (3.5 km) of tunnel without serious incident. The French machine was soon transferred to Liverpool, where it dug a ventilation tunnel for the Mersey Railway. The British machine was left in place, 130 feet (39.6 m) beneath the English Channel. The Undersea Continental Railway Company disappeared in 1886 after merging with the Channel Tunnel Company.

Watkin campaigned vigorously for another eight years, but to no avail. He retired from the railroad in 1894 and died in 1901.

If the military objections had been withdrawn, would the 19th century tunnel have been completed?

Beaumont and English showed how to build an undersea tunnel, but their "experimental" work was insignificant compared with the whole project. Watkin himself admitted that state support might be necessary before the connection could be completed. Beaumont's air-powered train was unlikely to achieve the scale expected, and the problems of constant ventilation and maintenance would be enormous. On the other hand, the advent of electric trains by the end of the century would greatly simplify this problem.

Illustration of how a modern tunnel boring machine works. © Pinterest

But geology is certainly on their side. In the late 1980s, during the construction of the modern tunnel, a Eurotunnel/TransManche boring machine passed through the original "Underwater Continental Railway Company" tunnel under the sea. The 1882 work was found to be watertight, with the rails and trolleys still in place: a reminder that someone had walked this path before.

By Peter Keeling

Translated by tamiya2

Proofreading/Rabbit's Light Footsteps

Original text/publicdomainreview.org/essay/the-early-history-of-the-channel-tunnel/

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