Linking the English Channel has always held promise, given the fact that both England and France were powerful maritime nations with great potential for trade. Earlier attempts to tunnel under the English Channel were thwarted due to engineering limitations and political resistance. With changing perspectives on national security and increased confidence in technological knowhow, these attempts were revisited.
Early visions for linking the English Channel
In the 1750s, the Amiens Academy of France floated a competition where the concept of an all-weather Channel crossing was first suggested. Earlier attempts at the Channel Tunnel were much like the shafts constructed for regular coal extraction. Albert Mathieu Favier, a French mining engineer proposed a tunnel for horse drawn carriages, since the steam engine was yet to be invented. The tunnel would be lit up by oil lamps and a mid-distance artificial island would allow changing of horses. The artificial island would be created from the Varne bank since it was only 49’ underwater. Technological limitations prevented these ideas from being developed.
Thome’ de Gamond and Sir John Hawkshaw
French engineer, Thome de Gamond devoted most of his life at finding a solution to build a fixed link across the channel. In 1833, he undertook a systematic geological and hydrographic survey for the project. He produced several designs over his career which included tubes, bridges, tunnels, floating ferries and an artificial isthmus. Thome de Gamonds’ proposal of 1857 involved not just the tunnel but also an artificial island midway where steam trains would resurface.
Sir John Hawkshaw, in 1865, proceeded to collect data on the sea-bed and helped establish an Anglo-French committee. This step helped start a diplomatic phase in the development of the Channel Tunnel. In the 1870s, there were fresh schemes which were reflective of the technical advancements. Engineering confidence was boosted by experience in projects which involved laying service cables underwater and constructing tunnels. A serious attempt begun in 1880 and about 2 km were bored from either side. However, this did not see fruition due to political concerns over security.
Changing Context of the English Channel
The 562 km long English Channel separates Great Britain from continental Europe. Only 34 km wide at its narrowest, it was natural that it drew engineers to work on physically connecting the two landmasses. Since this was seen as a valuable obstruction to warring forces, attempts to tunnel under the English Channel were viewed as a threat to security.
However, this perception changed when the German bombers crossed the Channel by air during the World War II. Further, the unarguable economic benefits of linking the two sides in addition to the cultural and political connectivity created a supportive context for the project.
The Competition
In 1985, the French and British Governments organized a competition for the fixed link and this included four main projects. The Europont was a suspended bridge scheme which used Kevlar cables and featured spans of about 4.5km. The scheme was rejected since its project cost was very high and the technology had been untested. The Euroroute project was developed around a bored undersea rail tunnel and a drive through bridge and tunnel scheme with artificial islands. The Channel Expressway had tunnels for both road and rail traffic. The winning scheme comprising of two running rail tunnels and a service tunnel was the Eurotunnel.
The Channel Tunnel
The 51 km long railway tunnel is the second longest railway tunnel after the Seikan Tunnel in Japan. The undersea section of the tunnel is at an average depth of about 50m below the Channel floor. The service tunnel plays a critical role in allowing an escape route and providing access to maintenance workers.
The moles or Tunnel Boring machines used to construct the tunnel are themselves an engineering marvel. The rotating cutters cut through the rock at the rate of about 4.6m an hour. The bored material is collected within the body and transported to a conveyor system. The freshly cut rock faces were lined with precast half-cylindrical concrete lining. A British team and a French team worked simultaneously from both ends and the two workforces met on December1, 1990.
Building a fixed link across the English Channel is a project which was required to overcome not only technical challenges but also to seek a political and economic context, conducive for its completion.
Sources:
Miller, Ron. Seven Wonders of Engineering: Twenty first century books, 2010.
Pompee, Pierre-Jean. Amicale des Batisseurs du tunnel sous La Manche.
Wilson Keith. Channel Tunnel Visions, 1850 – 1945: dreams and nightmares. Hambledon Press, 1994.
Anamika Mishra - Anamika holds a Master's degree in Urban Design with extensive experience in architectural and planning projects.
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