The Channel (Chunnel) Tunnel

Dr. R Kuberan, Ms. Sudeshna Mukherjee

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The idea to build a tunnel linking England and France first came about in 1802. Throughout the years many people had ideas and plans to link the two countries but it took more than 180 years to make it actually happen. The privately financed project, owned by Eurotunnel began in 1986. This lofty project would build an undersea leg that spans the English Channel between England and France. The project was completed in May of 1994 and opened for passenger service that November. For travellers and the haulage industry, the Channel Tunnel dramatically shortening travel time between London and Paris. Since commercial services started more than 366 million passengers have traveled through the Channel Tunnel, the equivalent to five times the population of the United Kingdom. Some facts and specifications of this tunnel:
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1. The Channel Tunnel is 31.4 miles long, making it the 11th longest tunnel in use (the longest is the Delaware Aqueduct, at 85.1 miles), and the fourth longest used by rail passengers. It has the longest undersea portion of any tunnel in the world (23.5 miles).
2. The project cost £4.65 billion (equivalent to £12 billion today), 80 per cent more than expected. Construction took six years (1988- 1994).
3. It was recognized as one of the “Seven Wonders of the Modern World” by the American Society of Civil Engineers, 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.
4. The first proposal for a tunnel under the Channel was put forward by Albert Mathieu, a French engineer - it included an artificial island half-way across for changing horses.
5. At the height of construction, 13,000 people were employed. Ten workers - eight of them British - were killed building the tunnel.
6. Englishman Graham Fagg and Frenchman Phillippe Cozette carried out the ceremonial break through on December 1, 1990.
7. They didn’t quite meet in the middle - the English side tunneled the greater distance.
8. The average depth of the tunnel is 50 metres below the seabed, and the lowest point 75 metres below. Much of the chalk marl spoil bored on the English side was deposited at Lower Shakespeare Cliff in Kent, now home to the Samphire Hoe Country Park.
9. There are actually three tunnels down there - two for trains and a smaller service tunnel that can be used in emergencies.
Dr. R Kuberan
Editor
Ms. Sudeshna Mukherjee
Assistant Editor
Civil Engineering and Construction Review
10. Up to 400 trains pass through the tunnel each day, carrying an average of 50,000 passengers, 6,000 cars, 180 coaches and 54,000 tonnes of freight.
11. Three fires have occurred (in 1996, 2006 and 2012) inside the tunnel that was significant enough for it to close. The most serious, on November 18, 1996, damaged 500 meters of the tunnel, affecting operations for six months. An automatic fire dousing system has now been installed.
12. A number of train failures have occurred. On December 18, 2009, five Euro star trains broke down, trapping 2,000 passengers for 16 hours without power, and many without food or water.
13. In 2014 a record 21 million passengers were transported between Britain and France using the tunnel - up from 7.3 million in 1995, its first full year in operation.
14. Shuttle trains are 775 meters long - the same as eight football pitches.
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15. The lining of the tunnel is designed to last for 120 years.
16. It takes around 35 minutes to travel the length of the Channel Tunnel.
Surveying undertaken in the 20 years before construction confirmed earlier speculations that a tunnel could be bored through a chalk marl stratum. The chalk marl is conducive to tunnelling, with impermeability, ease of excavation and strength. The chalk marl runs along the entire length of the English side of the tunnel, but on the French side a length of 5 kilometres (3 mi) has variable and difficult geology. The tunnel consists of three bores: two 7.6-metre (25 ft) diameter rail tunnels, 30 meters (98 ft) apart, and 50 kilometres (31 mi) in length with a 4.8-metre (16 ft) diameter service tunnel in between. The three bores are connected by cross-passages and piston relief ducts. The service tunnel was used as a pilot tunnel, boring ahead of the main tunnels to determine the conditions. English access was provided at Shakespeare Cliff, French access from a shaft at Sangatte. The French side used five tunnel boring machines (TBMs), the English side six. The service tunnel uses Service Tunnel Transport System (STTS) and Light Service Tunnel Vehicles (LADOGS). Fire safety was a critical design issue.
Between the portals at Beussingue and Castle Hill the tunnel is 50.5 kilometres (31 mi) long, with 3.3 kilometres (2 mi) under land on the French side and 9.3 kilometres (6 mi) on the UK side, and 37.9 kilometres (24 mi) under sea. It is the third-longest rail tunnel in the world, behind the Gotthard Base Tunnel in Switzerland and the Seikan Tunnel in Japan, but with the longest under-sea section. The average depth is 45 metres (148 ft) below the seabed. On the UK side, of the expected 5 million cubic metres (6.5×106 cu yd) of spoil approximately 1 million cubic metres (1.3×106 cu yd) was used for fill at the terminal site, and the remainder was deposited at Lower Shakespeare Cliff behind a seawall, reclaiming 74 acres (30 ha) of land. This land was then made into the Samphire Hoe Country Park. Environmental impact assessment did not identify any major risks for the project, and further studies into safety, noise, and air pollution were overall positive. However, environmental objections were raised over a high-speed link to London. Working from both the English side and the French side of the Channel, eleven tunnel boring machines or TBMs cut through chalk marl to construct two rail tunnels and a service tunnel. The vehicle shuttle terminals are at Cheriton (part of Folkestone) and Coquelles, and are connected to the English M20 and French A16 motorways respectively. Tunnelling commenced in 1988, and the tunnel began operating in 1994. In 1985 prices, the total construction cost was
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£4.650 billion (equivalent to £13 billion today), an 80% cost overrun. At the peak of construction 15,000 people were employed with daily expenditure over £3 million. Ten workers, eight of them British, were killed during construction between 1987 and 1993, most in the first few months of boring.
- The Channel Tunnel consists of two rail tunnels and one service tunnel, each 32 miles (51 kilometres) in length.
- The “Chunnel” connects Folkestone in Kent, England, with Coquelles in Pas-de-Calais, France.
- Many of the tunnel boring machines used on the Chunnel were as long as two football fields and capable of boring 250 feet a day.
- At its lowest point, it is 250 feet deep and at 24 miles long, the tunnel has the longest undersea portion of any in the world.
- When construction began, British and French tunnel workers raced to reach the middle of the tunnel first. The British won.
- The chalk marl excavated from Chunnel was used to create Samphire Hoe Park, a 74 acre nature reserve in Kent England.
Surveying undertaken in the 20 years before construction confirmed earlier speculations that a tunnel could be bored through a chalk marl stratum. The chalk marl was conducive to tunnelling, with impermeability, ease of excavation and strength. On the English side the chalk marl ran along the entire length of the tunnel, but on the French a length of 5 kilometres had variable and difficult geology. The tunnel consists of three bores: two 7.6-metre diameter rail tunnels, 30 metres apart, 50 kilometres in length with a 4.8-metre
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diameter service tunnel in between. There are also cross-passages and piston relief ducts. The service tunnel was used as a pilot tunnel, boring ahead of the main tunnels to determine the conditions. English access was provided at Shakespeare Cliff, French access from a shaft at Sangatte. The French side used five tunnel boring machines (TBMs), the English side six. The service tunnel uses Service Tunnel Transport System (STTS) and Light Service Tunnel Vehicles (LADOGS). Fire safety was a critical design issue. Between the portals at Beussingue and Castle Hill the tunnel is 50.5 kilometres long, with 3.3 kilometres under land on the French side and 9.3 kilometres on the UK side, and 37.9 kilometres under sea. It is the third-longest rail tunnel in the world, behind the Gotthard Base Tunnel in Switzerland and the Seikan Tunnel in Japan, but with the longest under-sea section. The average depth is 45 metres below the seabed. On the UK side, of the expected 5 million cubic metres of spoil approximately 1 million cubic metres was used for fill at the terminal site, and the remainder was deposited at Lower Shakespeare Cliff behind a seawall, reclaiming 74 acres of land. This land was then made into the Samphire Hoe Country Park. Environmental impact assessment did not identify any major risks for the project, and further studies into safety, noise, and air pollution were overall positive. However, environmental objections were raised over a highspeed link to London.
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