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| Channel Tunnel Le tunnel sous la Manche | |
| |
| Map of the Channel Tunnel | |
| Info | |
|---|---|
| Location | Beneath the English Channel (Strait of Dover) |
| Coordinates | Folkestone: , Coquelles: |
| Status | Active |
| Start | Folkestone, Kent, England |
| End | Coquelles, Pas-de-Calais, France |
| Operation | |
| Opened | 6 May 1994 |
| Owner | Eurotunnel |
| Operator(s) | Shuttle, Eurostar, EWS, SNCF |
| Technical | |
| Electrified | Yes |
The Channel Tunnel (French: le tunnel sous la Manche), also known as Chunnel or Eurotunnel is a 50.5 km (31.38 mi) undersea rail tunnel linking the United Kingdom and France. It runs beneath the English Channel at the Strait of Dover, connecting Folkestone, Kent in England to Coquelles near Calais in northern France.
Ideas for a cross-Channel fixed link existed as early as 1802. In 1988 Eurotunnel began construction, with Tunnel Boring Machines working from both the UK and France. By 1994 the tunnel commenced operating its through-rail passenger services that link London to Paris and Brussels, through-rail freight services and vehicle shuttle services. The project\'s cost overran by 80%. Concessionaire Eurotunnel overestimated tunnel traffic and has met financial difficulty.
In 1996 a fire disrupted operation of the tunnel. In 1996 the American Society of Civil Engineers selected the tunnel to be one of the Seven Wonders of the Modern World.
Contents |
Proposals for a fixed-link to cross the English Channel go back to Albert Mathieu\'s 1802 plan involving horse-drawn carts and a constructed mid-Channel island. Until the advent of air power in 1955, British political and press pressure over compromised national security stalled attempts to construct a tunnel. In 1974, French and UK government funded construction commenced on both sides of the Channel but the project was cancelled by the UK government due to financial concerns. In 1985 the UK and French governments invited submissions for a fixed link. Eurotunnel, a group of ten construction companies and five banks, was awarded the project, which was a triple-bore railway tunnel based on the 1974 attempt. Tunnelling commenced in 1988 and the tunnel began operating in 1994. In 1985 prices, the total construction cost was £4650 million, an 80% cost overrun. At the peak of construction 15,000 people were employed with daily expenditure over £3 million.Anderson, pp. xvi Ten workers died during construction.Harlow, John. "Phantom Trains Wreak Havoc in Channel Tunnel", The Sunday Times, Times Newspapers Ltd, 2 April 1995. ingenious: Navvies. ingenious. Retrieved on 2008-03-11.
Three services use the tunnel: Le Shuttle — a roll-on roll-off shuttle service for road vehicles including freight lorries, Eurostar — through rail services for passengers, and through rail freight services. Eurotunnel\'s traffic predictions for the tunnel were overestimates and Eurotunnel has been financially challenged. In 1996 a heavy goods vehicle shuttle wagon fire caused damage and restricted use of the tunnel, although nobody was seriously hurt in the incident.
Five years after the opening of the tunnel there were few and small impacts on the wider economy, and it was difficult to identify major developments associated with the tunnel. The tunnel is a pathway for illegal immigration.
In the 1996 Tom Cruise action film Mission: Impossible a helicopter is flown into the tunnel, crashes and explodes."Mission is possible: Helicopter rides through Chunnel", The Evening Standard, Associated Newspapers, 27 August 1998. Retrieved on 2008-03-10. In 1996 the American Society of Civil Engineers with Popular Mechanics magazine selected the tunnel as one of the Seven Wonders of the Modern World.Reynolds, Christopher. "Seven Wonders of the World: The Modern List", The Plain Dealer, 19 May 1996. Retrieved on 2008-03-13.
Thomé de Gamond\'s 1856 plan for a cross-Channel link, with a port/airshaft on the Varne sandbank mid-Channel.
In 1802 French mining engineer Albert Mathieu put forward a proposal to tunnel under the English Channel, with illumination from oil lamps, horsedrawn coaches, and an artificial island mid-Channel for chaning horses.Whiteside p.17 In the 1830s Frenchman Aimé Thomé de Gamond performed the first geological and hydrographical surveys on the Channel, between Calais and Dover. Thomé de Gamond explored several schemes. In 1856 he presented a proposal to Napoleon III, a mined railway tunnel from Cap Gris-Nez to Eastwater Point with a port/airshaft on the Varne sandbankWhiteside p.18-23 at a cost of 170 million francs, or less than 7 million pounds sterling."The Proposed Tunnel Between England and France", The New York Times, August 7, 1866. Retrieved on 2008-01-03.
After 1867 British men William Low and Sir John Clarke Hawkshaw promoted ideas but none were executed. In 1876 an official Anglo-French protocol was established for a cross-Channel railway tunnel. In 1881 British railway entrepreneur Sir William Watkin and French Suez Canal contractor Alexandre Lavalley were in the Anglo-French Submarine Railway Company that conducted exploratory work on both sides of the Channel. On the English side a 2.13 m diameter Beumont-English boring machine dug a 1893 m pilot tunnel from Shakespeare Cliff. On the French side a similar machine dug 1669 m from Sangatte. The project was abandoned in May 1882 due to British political and press campaigns arguing that a tunnel would compromise Britain\'s national defences.
With air power now dominant, in 1955 defence arguments were accepted to be irrelevant. The British and French governments supported technical and geological surveys. In 1974 construction work commenced on both sides of the Channel, the project was government funded, used twin tunnels on either side of a service tunnel with capability for car shuttle wagons. To the dismay of the French partners in January 1975 the British government cancelled the project; the government changed to Labour, there was uncertainty about EC membership, cost estimates had ballooned to 200% and the national economy was troubled. By this time the British Priestly TBM was ready and the Ministry of Transport was able to do a 300 m experimental drive.
In 1979 "The Mousehole Project" was suggested when conservatives came to power in Britain. The concept was a single rail tunnel with a service tunnel, without shuttle terminals. The British government took no interest in funding the project but Prime Minister Margaret Thatcher said she had no objection to a privately funded project. In 1981 British and French leaders Margaret Thatcher and François Mitterrand agreed to set up a working group to look into a privately funded project, in April 1985 promoters were formally invited to submit scheme proposals. The four shortlisted submissions were: from Channel Tunnel Group/France-Manche (CTG/F-M) a rail proposal based on the 1975 scheme; Eurobridge - a 4.5 km span suspension bridge with roadway in an enclosed tube; Euroroute - a 21 km tunnel between artificial islands approached by bridges; Channel Expressway - large diameter road tunnels with mid channel ventilation towers. The cross-Channel ferry industry protested under the name "Flexilink". In 1975 there was no campaign, with one of the largest ferry operators (Sealink) being state owned. Flexilink continued rousing opposition throughout 1986 and 1987. Public opinion strongly favoured a drive through tunnel but ventilation issues, accident management, and driver mesmurisation led to the only rail submission shortlisted, CTG/F-M, being awarded the project.Wilson pp. 14-21
A flow chart describing the organisation structure used on the project.
The Channel Tunnel Group consisted of two banks and five construction companies, the French equivalent group France-Manche consisted of three banks and five construction companies. The role of the banks was to advise on financing and secure loan commitments. On 2 July 1985 the groups formed Channel Tunnel Group/France-Manche (CTG/F-M). Their submission to the British and French governments was drawn from the 1975 project, it included 11 volumes and a substantial environmental impact statement.
The design and construction was done by the ten construction companies in the CTG/F-M group. The French terminal and boring from Sangatte was undertaken by the five French construction companies in the joint venture group GIE Transmanche Construction. The English Terminal and boring from Shakespeare Cliff was undertaken by five English construction companies in the Trankslink Joint Venture. The two partnerships were linked by TransManche Link (TML), a binational project organisation.
In France, with its long tradition of infrastructure investment, the project garnered widespread approval and in April 1987 the French National Assembly gave unanimous support, after a public inquiry the Senate gave unanimous support in June 1987. In Britain select committees examined the proposal, making history by holding hearings outside of Westminster - in Kent. In February 1987 the third reading of the Channel Tunnel Bill occurred in the House of Commons, carried 94 votes to 22. The Channel Tunnel Act passed into British law in July.
The Channel Tunnel is a build-own-operate-transfer (BOOT) project with a concession.Flyvberg p. 96/97 TML would design and build the tunnel, but financing was through a separate legal entity: Eurotunnel. Eurotunnel absorbed CTG/F-M and signed a construction contract with TML, however, the British and French governments controlled final engineering and safety decisions. The British and French governments gave Eurotunnel a 55 (later 65) year operating concession to repay loans and pay dividends.
A Railway Usage Agreement was signed between Eurotunnel, British Rail and SNCF guaranteeing future revenue in exchange for the railways obtaining half of the tunnel\'s capacity.
Private funding for such a complex infrastructure project was of unprecedented scale. An initial equity of £45 million raised by CTG/F-M, increased by £206 million private institutional placement, £770 was raised in a public share offer that included press and television advertisements, a syndicated bank load and letter of credit arranged £5 billion. Privately financed, the total investment costs at 1985 prices were £2600 million. At the 1994 completion actual costs were, in 1985 prices, £4650 million; an 80% cost overrun.Flyvberg p. 12 The cost overrun was partly due to enhanced safety, security, and environmental demands. Financing cost were 140% higher than forecast.Flyvberg p. 3
| Key dates | |
|---|---|
| February 1986 | The Treaty of Canterbury was signed allowing the project to proceed. |
| June 1988 | First tunnelling commenced in France. |
| December 1988 | UK TBM commenced operation. |
| December 1990 | The service tunnel broke through under the Channel. |
| May 1994 | The tunnel was formally opened by the Queen and President Mitterand. |
| Mid 1994 | Freight and passenger services commenced operation. |
| Source:Anderson, pp. xv | |
A small pilot hole allowed the service tunnel to brake through without ceremony on 30 October 1990.Glenn Frankel. "Britain and France Link Up--at Last", The Washington Post, 3 October 1990. On 1 December 1990 Englishman Graham Fagg Frenchman Phillipe Cozette broke through the service tunnel with the media watching."Chunnel birthday", Evening Mail, Birmingham Post & Mail Ltd, 2 December 2000.
The tunnel was officially opened by Queen Elizabeth II and French President François Mitterrand in a ceremony held in Calais on 6 May 1994. The Queen travelled through the tunnel to Calais on a Eurostar train which stopped nose to nose with the train which carried President Mitterrand from Paris."1994: President and Queen open Chunnel", On This Day, BBC News, 1994-05-06. Retrieved on 2008-01-12. Following the ceremony President Mitterrand and the Queen travelled on Le Shuttle to a similar ceremony in Folkestone.
Eurotunnel completed the tunnel on time. The Channel Tunnel Rail Link (CTRL), now called High Speed 1, runs 69 miles from St Pancras station in London to the Channel Tunnel portal at Folkestone in Kent. It cost £5.8 billion. On September 16 2003 UK Prime Minister Tony Blair opened the first section of High Speed 1, from Folkestone to north Kent. On 6 November 2007 the Queen officially opened High Speed 1 and St Pancras International station.Woodman, Peter. "High-speed Rail Link Finally Completed", Press Association National Newswire, 14 November 2007.
On the completed High Speed 1, trains travel at 186 miles per hour. The Eurostar journey from London to Paris takes 2 hours 15 minutes, London to Brussels takes 1 hour 51 minutes"New high-speed rail line opens to link Britain to Europe", Channel NewsAsia, MediaCorp News, 15 November 2007.
A Channel Tunnel traffic graph showing the number of passengers and tonnes of freight.
Services offered by the tunnel include:
Both the freight and passenger traffic forecasts that led to the construction of the tunnel were largely and systematically overestimated. Particularly, Eurotunnel\'s commissioned forecasts were over predictions. Although the captured share of Channel crossings (competing with air and sea) was forecast correctly, high competition and reduced tariffs has led to low revenue. Overall cross-Channel traffic was overestimated. A cost benefit analysis of the Channel Tunnel indicated that the British economy would have been better off if the Tunnel had never been constructed.
Channel Tunnel passenger volumes were overestimated, peaking at 18.4 million in 1998, and down to 14.7 million in 2003. At the time of deciding to build the tunnel 15.9 million passengers were predicted for Eurostar trains in the opening year. In 1995, the opening year, actual numbers were 2.9 million. Passenger numbers in 2001 were 6.9 million.
Tunnel freight traffic volumes have been erratic, with a decrease during 1997 due to a closure caused by a fire in a freight shuttle - the total freight crossings increased over the period, indicating the substitutability of the tunnel by sea crossings. The tunnel has achieved a cross-Channel freight traffic market share close or above Eurotunnel\'s 1980s predictions but Eurotunnel\'s 1990 and 1994 predictions were overestimates. The first year freight prediction was 7.2 million gross tonnes, however, the 1995 figure was 1.3 million gross tonnes, in 2001 this had increased to 2.4 million tonnes.Flyvberg p. 22 Freight traffic growth has occurred since opening, with 18.4 millions tonnes recorded in 2003.Ricard Anguera (May 2006). "The Channel Tunnel—an ex post economic evaluation". Transportation Research Part A: Policy and Practice 40 (4): 291-315.
Shares in Eurotunnel were issued at £3.50 per share on 9 December 1987. By mid 1989 the price rose to £11.00. Delays and cost overruns led to the share prices dropping, during demonstration runs in October 1994 the share price reached an all-time low value. Eurotunnel suspended payment on it debt in September 1995 to avoid bankruptcy. In December 1997 the British and French governments extended Eurotunnel\'s operating concession by 34 years to 2086. Financial restructuring of Eurotunnel occurred in mid 1998, reducing debt and financial charges. Despite the restructuring The Economist reported in 1998 that to break even Eurotunnel would have to increase fares, traffic and marketshare for sustainability.Flyvberg p. 32-34
Under the terms of the Concession Eurotunnel was obliged to investigate a cross-Channel road tunnel. In December 1999 road and rail tunnel proposals were presented to the British and French governments, but it was stressed that there was not enough demand for a second tunnel."Eurotunnel unveils plans for second link", Birmingham Post, Birmingham Post & Mail Ltd, 6 January 2000.
A detailed three-way treaty between the United Kingdom, France, and Belgium governs border controls, with the establishment of control zones wherein the officers of the other nation may exercise limited customs and law enforcement powers. For most purposes these are at either end of the tunnel, with the French border controls on the UK side of the tunnel and visa versa. For certain city-to-city trains the train itself represents a control zone.The CPS: Channel Tunnel. Crown Procecution Service. Retrieved on 2008-03-11. A binational emergency plan coordinates UK and French emergency activities.30 November would presently stop running.Dominic O\'Connell. "Chunnel cash row threatens freight trains", The Sunday Times, September 3 2006. Retrieved on 2006-09-03.
On 18 November 1996 a fire broke out on a heavy goods vehicle shuttle wagon within the tunnel, nobody was seriously hurt in the incident. The exact cause is unknown, although it was not a Eurotunnel equipment or rolling stock problem, it may have been due deliberate setting on fire of a heavy goods vehicle. It is estimated that the heart of the fire reached 1000°C, the tunnel was severely damaged over 46 m with some 500 m affected to some extent. Full operation was able to be recommence 6 months after the fire.C. J. Kirkland (2002). "The fire in the Channel Tunnel" (pdf). Tunnelling and Underground Space Technology 17: 129-132. A less severe incident occurred on 21 August 2006, when a lorry aboard a shuttle train caught fire."Lorry fire closes Channel Tunnel", BBC Online, 21 August 2006. Retrieved on 2006-08-21.
A 1996 report from the European commission predicted that Kent and Nord-Pas-de-Calais had to face increased traffic volumes due to general growth of cross-Channel traffic and traffic attracted by the tunnel. In Kent, a high speed rail line to London would transfer traffic from road to rail.European Commission p.220-222 Kent\'s regional development would benefit from the tunnel, but being so close to London restricts the benefits. Gains are in the traditional industries. Gains largely dependent on the development of the Ashford international passenger station, without which Kent would be totally dependent on London\'s expansion. Nord-Pas-de-Calais enjoys a strong internal symbolic effect of the Tunnel which results in significant gains in manufacturing.European Commission p.248-252
The removal of a bottleneck like the Channel Tunnel does not necessarily induce economic gains in all adjacent regions, the image of a region being connected to the European high-speed transport and active political response are more important for regional economic development. Tunnel induced regional development is small compared to general economic growth.Fayman, Sonia; Metge, Pierre (September 1995). "The regional impact of the Channel Tunnel: Qualitative and quantitative analysis". European Planning Studies 3 (3): 333.
The South East of England is likely to benefit developmentally and socially from faster and lower cost transport to continental Europe, but they are unlikely to be equally distributed throughout the region. The overal the environmental impact is almost certainly negative.Button, Kenneth (July 1990). "The Channel Tunnel: The Economic Implications for the South East of England". The Geographical Journal 156 (2): 187-199.
Five years after the opening of the tunnel there were few and small impacts on the wider economy, and it was difficult to identify major developments associated with the tunnel.Flyvberg p. 68
Illegal immigrants and would-be asylum seekers have been known to use the tunnel to attempt to enter Britain. By 1997, the problem had already attracted international press attention, and the French Red Cross opened a refugee centre at Sangatte in 1999, using a warehouse once used for tunnel construction; by 2002 it housed up to 1500 persons at a time, most of them trying to get to the UK.Pierre Kremer. "Sangatte: A place of hope and despair", The Magazine of the International Red Cross and Red Crescent Movement, February 2002. Retrieved on 2006-08-04. At one point, large numbers came from Afghanistan, Iraq and Iran, but African and Eastern European countries are also represented.Caryl Phillips. "Strangers in a strange land", The Guardian, November 17, 2001. Retrieved on 2006-08-04. Most migrants who got into Britain found some way to ride a freight train, but others used Eurostar. Though the facilities were fenced, airtight security was deemed impossible; refugees would even jump from bridges onto moving trains. In several incidents persons were injured during the crossing; others tampered with railway equipment, causing delays and requiring repairs.Avril Stephens. "Desperate journeys fraught with danger", CNN, July 31, 2001. Retrieved on 2006-08-04. Eurotunnel said it was losing £5m per month due to the problem."Europe\'s most notorious refugee camp", BBC News, 12 July 2002. Retrieved on 2006-08-05. Over a dozen refugees died in various crossing attempts. In 2001 and 2002, several riots broke out at Sangatte and groups of refugees (up to 550 in a December 2001 incident) stormed the fences and attempted to enter en masse.Paul Webster. "Police braced for new tunnel raid", The Guardian, December 27, 2001. Retrieved on 2006-08-04. Immigrants have also arrived as legitimate Eurostar passengers without proper entry papers."UK/Ireland: Asylum (news digest)", Migration News, 1998 (?). Retrieved on 2006-08-04.
Local authorities in both France and the UK called for the closure of Sangatte, and Eurotunnel twice sought an injunction against the centre. The United Kingdom blamed France for allowing Sangatte to open, and France blamed the UK for its lax asylum rules and the EU for not having a uniform immigration policy. The cause célèbre nature of the problem even included journalists detained as they followed refugees onto railroad property.2001 World Press Freedom Review: France. International Press Institute. Retrieved on 2006-08-04. In 2002, after the European Commission told France that it was in breach of European Union rules on the free transfer of goods, due to the delays and closures as a result of its poor security, a double fence was built at a cost of £5 million, reducing the numbers of refugees detected each week reaching Britain on goods trains from 250 to almost none."Sangatte asylum talks due", BBC, 26 September, 2002. Retrieved on 2006-08-04. Other measures included CCTV cameras and increased police patrols."Tunnel security to be tightened", BBC, 31 May, 2002. Retrieved on 2006-08-04. At the end of 2002, the Sangatte centre was closed after the UK and France agreed to take shares of the refugees.Philip Delves Broughton and Andrew Sparrow. "Blunkett reaches deal to shut Sangatte camp", Daily Telegraph, September 27 2002. Retrieved on 2006-08-04.
Surveying undertaken in the twenty years prior to tunnel construction confirmed earlier suspicions that a tunnel route could be bored through a chalk marl stratum. The chalk marl was conducive to tunnelling, with impermeability, ease of excavation and strength. While on the English side the chalk marl ran along the entire length of the tunnel, on the French side a length of 5 km had variable and difficult geology. The Channel Tunnel consists of three bores: two 7.6 m diameter rail tunnels, 30 m apart, 50 km in length with a 4.8 m diameter service tunnel in between. There are also cross-passages and piston reliefs 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, while French access came from a shaft at Sangatte. The French side used five Tunnel Boring Machines (TBMs), the English side used six. Trains that operate in the tunnel are: Le Shuttle locomotives for vehicle-passenger transport, Class 92 locomotives for hauling freight and overnight passenger trains and Eurostar trains based on the French TGV. The service tunnel uses Service Tunnel Transport System (STTS) and Light Service Tunnel Vehicles (LADOGS). Fire safety was a critical design issue. Terminal sites are located at Cheriton (Folkestone in England) and Coquelles (Calais in France).
From the Beussingue to Castle Hill portals the tunnel is 50.5 km long, with 3.3 km underland on the French side, 9.3 km underland on the UK side and 37.9 km undersea.Institute of Civil Engineers p. 95 On the UK side, of the expected 5 million m³ of spoil approximately 1 million m³ was used for fill at the terminal site, and the remainder was deposited at Lower Shakespeare Cliff behind a seawall, reclaiming land.Institute of Civil Engineers p. 208 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.Flyvberg p. 51
Marine soundings and samplings by Thomé de Gamond were carried out during 1833-67 established the seabed depth, a maximum of 55 m, and the continuity of geological strata (layers). Surveying continued over many years. 166 marine and 70 land deep boreholes were drilled. Over 4000 line kilometers of marine geophysical survey was completed.
Surveys were undertaken in 1958-59, 1964-65, 1972-74 and 1986-88. Surveying in 1958-59 catered for immersed tube and bridge designs as well as a bored tunnel, and thus a wide area was investigated. At this time marine geophysics surveying for engineering projects was in its infancy - with poor positioning and resolution from seismic profiling. The 1964-65 surveys concentrated on a northerly route that left the English coast at Dover harbour, using 70 boreholes an area of deeply weathered rock with high permeability was located just south of Dover harbour. Given the previous survey results and access constraints a more southerly route was investigated in the 1972-73 survey and the route was confirmed to be feasible. Information for the tunnelling project also came from work before the 1975 cancellation. On the French side at Sangatte a deep shaft with adits was made. On the English side at Shakespeare Cliff the government allowed 250 m of 4.5 m diameter tunnel to be driven. The actual tunnel alignment, method of excavation and support were essentially the same as the 1975 attempt. In the 1986-97 survey, previous findings were reinforced and the nature of the gault clay and tunnelling medium, chalk marl that made up 85% of the route, were investigated. Geophysical techniques from the oil industry were employed.Kirkland pp.22-26
Geological profile along the tunnel as constructed. For the majority of its length the tunnel bores through a chalk marl stratum (layer).
Successful tunnelling under the channel required a sound understanding of the topography and geology and the selection of the best rock strata to tunnel through. The geology generally consists of north-easterly dipping Cretaceous strata, part of the northern limb of the Wealden-Boulonnais dome. Characteristics include:
On the English side of the channel the strata dip less than 5°, however on the French side this increases to 20°. Jointing and faulting is present on both the English and French sides. On the English side only minor faults of displacement less than 2 m exists. On the French side displacements of up to 15 m are present due to the Quenocs anticlinal fold. The faults are of limited width, filled with calcite, pyrite and remoulded clay. The increased dip and faulting restricted the selection of route on the French side.
To avoid confusion microfossil assemblages were used to classify the chalk marl. On the French side, particularly near the coast, the chalk was harder and more brittle and fractured than on the English side. This led to the adoption of different tunnelling techniques on the French and English sides.
No major geological hazards were identified, however the Quaternary undersea valley Fosse Dangaered, and Castle Hill landslip located at the English portal were concerning. Identified by the 1964-65 geophysical survey the Fosse Dangaered is an infilled valley system extending 80 m below the seabed, 500 m south of the tunnel route, located mid channel. A 1986 survey showed that a tributary crossed the path of the tunnel and so the tunnel route was made as far north and deep as possible. The English terminal had to be located in the Castle Hill landslip, which consists of displaced and tipping blocks of lower chalk, glauconitic marl and gault debris. Thus the area was stabilised by buttressing and inserting drainage adits.
The service tunnels were pilot tunnels preceding the main tunnels so that the geology, areas of crushed rock and zones of high water inflow could be predicted. Exploratory probing took place in the service tunnels in the form of extensive forward probing, vertical downward probes and sideways probing.Kirkland pp.21-50
Tunnelling between England and France was a major engineering challenge with just one precedent - the undersea Seikan Tunnel in Japan. The major risk with underwater tunnels is major water inflow due to the water pressure from the sea above under weak ground conditions. The Channel Tunnel also had the challenge of time - being privately funded early financial return was paramount.
.svg/58px-Eurotunnel schema (empty service).svg){kind=spacer}
Typical tunnel cross section.
The objective was to construct: two 7.6 m diameter rail tunnels, 30 m apart, 50 km in length; a 4.8 m diameter service tunnel between the two main tunnels; pairs of 3.3 m diameter cross-passages linking the rail tunnels to the service tunnel at 375 m spacing; piston relief ducts 2 m diameter connecting the rail tunnels at 250 m spacing; two undersea crossover caverns to connect the rail tunnels.Kirkland pp.63-128
The service tunnel always preceded the main tunnels by at least 1 km to ascertain the ground conditions.
Experience with tunnelling through chalk had occurred in the mining industry.
The undersea crossover caverns where a complex engineering problem. The French cavern was based on the Mount Baker Ridge freeway tunnel in the USA. The UK cavern was dug from the service tunnel ahead of the main tunnels to avoid delay.
Precast segmental linings in the main TBM drives were used, but different solutions were on the English and French sides. On the French side neoprene and grout sealed bolted linings made of cast iron or high strength reinforced concrete. On the English side the main requirement was for speed, bolting of cast iron lining segments was only carried out in areas of poor geology.
On the French side a 55 m diameter 75 deep grout-curtained shaft at Sangatte was used for access. On the English side a marshalling area was located 140 m below the top of Shakespeare Cliff, the New Austrian Tunnelling Method (NATM) was first applied in the chalk marl here. On the English side the land tunnels were driven not from Folkestone but from the same place as the marine tunnels, Shakespeare Cliff. The platform at the base of the cliff was not large enough for all of the drives, and despite environmental objections tunnel spoil was placed behind a reinforced concrete sea wall at Shakespeare Cliff, under the condition of placing the chalk in enclosed lagoon to avoid wide dispersal of chalk fines. Due to limited space the precast lining factory was located at the Isle of Grain in the Thames estuary.
On the French side, due to the greater permeability of water a earth pressure balance TBMs with open and closed modes was utilised. The TBMs were of a closed nature during the initial 5 km but then operated as open, once boring through the chalk marl stratum. This minimised the impact to the ground and allowed high water pressures to be withstood, it also alleviated the need to grout ahead of the tunnel. The French effort required five TBMs: two main marine tunnel machines, one main land tunnel machine (the short land drives of 3 km allowed one TBM to complete the first drive then reverse direction and complete the other), and two service tunnel machines.
On the English side the simpler geology allowed faster open-faced TBMs.Kirkland pp.29 Six machines where used, all commencing digging from Shakespeare Cliff, three marine bound and three for the land tunnels. Towards the completion of the undersea drives the UK TBMs were driven steeply downwards and buried clear of the tunnel. The French TBMs then completed the tunnel and were dismantled.Wilson p. 44
A 900 mm gauge railway was used on the English side during construction.Kirkland pp.117-128
The Channel Tunnel exhibit at the National Railway Museum in York, England. The exhibit shows the circular cross section of the tunnel with the catenary (overhead) wires powering a Eurostar train.
Interior of Eurotunnel Shuttle, a vehicle shuttle train.
Three communication systems exist for the tunnel: concession radio (CR) for mobile vehicles and personnel within Eurotunnel\'s Concession (termianls, tunnels, coastal shafts); Track-to-train radio (TTR for secure speech and data between trains and the railway control centre); Shuttle internal radio (SIR) for communication between shuttle crew and communication to passengers over car radios.Kirkland pp.129-132
All tunnel services run on electricity, shared equally from both English and French sources. Power is delivered to the locomotives via an overhead catenary system.Kirkland pp.134-148
A cab signalling system is used that gives information directly to train drivers on a display. There is automatic train protection (ATP) that stops the train if the speed differs from that indicated on the in-cab display. TVM430, as used on TGV Nord, is used in the tunnel. Kirkland pp.149-155
Shuttle trains traverse a figure eight at the terminals to reduce uneven wear on the wheels. The American Sonneville International Corporation track system was used in the tunnel, ballasted track was ruled out due to maintenance constraints and a need for geometric stability. The Sonneville system has UIC60 rails on 900A grade resting on microcelluar EVA pads, bolted into concrete. Kirkland pp.157-174
Initially 38 Le Shuttle locomotives were commissioned, they always work in pairs with one at each end of a shuttle train. The shuttles themselves have two separate halves: single and double deck. Each half has two loading/unloading wagons and 12 carrier wagons. Eurotunnel\'s original order was for 9 shuttles.
46 Class 92 locomotives for hauling freight and overnight passenger trains were commissioned, that can run on both overhead AC and third-rail DC power. Freight shuttles also have two halves, with each half containing one loading wagon, one unloading wagon and 14 carrier wagons. There is a club car behind the leading locomotive. Eurotunnel originally ordered 6 freight shuttles.
31 Eurostar trains, based on the French TGV with many modifications for safety within the tunnel, were initially commissioned, with split ownership between British Rail, French National Railway Company and National Railway Company of Belgium. British Rail ordered 7 more for services north of London.Kirkland pp.175-211
The service tunnel is used for access to technical equipment in cross-passages and equipment rooms, to provide fresh-air ventilation, and for emergency evacuation. The Service Tunnel Transport System (STTS) allow fast access to all areas of the tunnel. The service vehicles are rubber-tyred with a buried guidance wire system. 24 STTS vehicles were made, they are used mainly for maintenance but also firefighting and in emergencies. "Pods" with different purposes, up to a payload of 2.5-5 tonnes are inserted into the side of the vehicles. The STTS vehicles cannot turn around within the tunnel, they are driven from either end. The maximum speed is 80 km/h when the steering is locked.
A smaller fleet of 15 Light Service Tunnel Vehicles (LADOGS) were introduced to supplement the STTSs. The LADOGS have a short wheelbase with a 3.4 m turning circle allowing two-point turns within the service tunnel. Steering cannot be locked like the STTS vehicles, maximum speed is 50 km/h. Pods upto 1 tonne can be loaded onto the rear of the vehicles.
Drivers in the tunnel sit on the right, and the vehicles drive on the left. Due to the risk of French personnel driving on their native right side of the road, sensors in the road vehicles alert the driver if the vehicle strays to the right side of the tunnel.Kirkland pp.247-254
The three tunnels contain 6000 tonnes of air that needs to be conditioned for comfort and safety. Air is supplied from ventilation buildings at Shakespeare Cliff and Sangatte, with each building capable of full duty providing 100% standby capacity. Supplementary ventilation also exists on either side of the tunnel. In the event of a fire, ventilation is used to keep smoke out of the service tunnel and move smoke in one direction in the main tunnel to give passengers clean air.
Trains travelling at high speed create a piston-effect pressure changes that can affect passenger comfort, ventilation systems, tunnel doors, fans and the structure of the trains, and drag on the trains.Kirkland pp.212-230 Piston relief ducts of 2 m diameter were chosen to solve the problem, with 4 ducts per kilometer to give close to optimum results. Unfortunately this design led to unacceptable lateral forces on the trains so a reduction in train speed and restrictors were installed in the ducts.The Channel Tunnel Experience Lessons for the Future pp.19-23
The Channel Tunnel was the first mainline railway tunnel to have special cooling equipment. Heat is generated from traction equipment and drag. The design limit was set at 30°C, using a mechanical cooling system with refrigeration plants on both the English and French sides that run chilled water circulating in pipes within the tunnel.
The safety issue of a fire on a passenger-vehicle shuttle garnered much attention, with Eurotunnel itself noting that fire was the risk gathering the most attention a 1994 Safety Case due to three reasons: ferry companies opposed to passengers being allowed to remain with their cars; Home Office statistics indicating that car fires had doubled in ten years; and the long length of the tunnel.
Eurotunnel commissioned the UK Fire Research Station to give reports of vehicles fires, as well liaising with Kent Fire Brigade to gather vehicle fire statistics over one year. Fire tests took place at the French Mines Research Establishment with a mock wagon used to investigate how cars burned.Kirkland pp.231-240
The door systems which close off the wagon ends during transit of the tunnel are designed to resist a fire inside the wagon for up to 30 min, i.e. for a period longer than the transit time of 27 min
The wagon door systems are designed to withstand fire inside the wagon for 30 minutes, longer than the transit time of 27 minutes. Wagon air conditioning units help to purge dangerous fumes from inside the wagon before travel. Each wagon has a fire detection and extinguishing system, with sensing of ions, or ultra-violet radiation, smoke and gases that can trigger halon gas to quell a fire. Since the Heavy Goods Vehicle (HGV) wagons are not covered, fire sensors are located on the loading wagon and in the tunnel itself. A water main in the service tunnel provides water to the main tunnels at 125 m intervals.
The ventilation system can control smoke movement. Special arrival sidings exist to accept a train that is on fire, the train should not stop whilst on fire in the tunnel. Eurotunnel has banned a wide range of hazardous good from travelling in the tunnel. Two STTS vehicles with firefighting pods are on duty at all times, with a maximum delay of 10 minutes before they reach a burning train.
The British terminal at Cheriton in west Folkestone, from the Pilgrims\' Way. The terminal services shuttle trains that carry vehicles, and is linked to the M20 motorway
A vehicle entering a shuttle wagon at the French terminal.
Terminal sites are located at Cheriton (Folkestone in England) and Coquelles (Calais in France). The terminals were designed to transfer vehicles from the motorway onto trains at a rate of 700 cars and 113 heavy vehicles per hour - a unique facility. The UK site uses the M20 motorway. The terminals are organised with the frontier controls juxtaposed with the entry to the system to allow travellers to go otno the motorway at the destination country immediately after leaving the shuttle. The area of the UK site was severely constrained and the design was challenging. The French layout was achieved more easily. To achieve design throughput the shuttle accept cars on double-decks, for flexibility ramps were placed inside the shuttles to provide access to the top decks.Kirkland pp.255-270 At Folkestone there is 20 km of main-line track and 45 turnouts with eight platforms. At Calais there is 30 km of track with 44 turnouts. At the terminals, the shuttle trains traverse a figure of eight to reduce wear on the wheels.
Wikimedia Commons has media related to:
| Channel Tunnel | |
|---|---|
| Construction | Fixed Link Treaty - TransManche Link - High Speed 1 |
| Corporate | Eurotunnel Group - Eurostar (U.K.) Ltd. - SNCF - SNCB |
| Services | Eurostar - Eurotunnel Shuttle - Europorte 2 |
| Other | Rail transport in France - Rail transport in the United Kingdom |
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