The Channel Tunnel is a 50.5-kilometre (31.4 mi) undersea rail tunnel linking Folkestone, Kent, in the United Kingdom with Coquelles,Pas-de-Calais, near Calais in northern France beneath the English Channel at the Strait of Dover. At its lowest point, it is 75 m (250 ft) deep. At 37.9 kilometres (23.5 mi), the Channel Tunnel possesses the longest undersea portion of any tunnel in the world, although the Seikan Tunnel in Japan is both longer overall at 53.85 kilometres (33.46 mi) and deeper at 240 metres (790 ft) below sea level.
Working from both the English side and the French side of the Channel, eleven tunnel boring machines 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 and French motorways (M20 and A16 respectively).
Tunnelling commenced in 1988, and the tunnel began operating in 1994. In 1985 prices, the total construction cost was £4.650 billion (equivalent to £12 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.
Services offered by the tunnel are:
- Eurotunnel Shuttle (formerly Le Shuttle) roll-on roll-off shuttle service for road vehicles,
- Eurostar passenger trains,
- through freight trains.
Both the freight and passenger traffic forecasts that led to the construction of the tunnel were largely and universally 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.
With the EU's liberalisation of international rail services, the tunnel and High Speed 1 have been open to competition since 2010. There have been a number of operators interested in running services, through the tunnel and along High Speed 1 to London. Deutsche Bahn did in June 2013 after several years of struggle get a license to operate Frankfurt – London trains, however they don't expect to run any before 2016, because of delivery delays of the custom-made trains.
Railway design
Communications
There are three communication systems in the tunnel: concession radio (CR) for mobile vehicles and personnel within Eurotunnel's Concession (terminals, 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 to passengers over car radios. This service was discontinued within one year of opening because of drivers' difficulty setting their radios to the correct frequency (88.8 MHz).
Power supply
All tunnel services run on electricity, shared equally from English and French sources. Power is delivered to the locomotives via an overhead line (catenary) at 25 kV 50 Hz.
A large proportion of the railway south of London uses a 750 V DC third rail to deliver electrical power, but since the opening of High Speed 1 there is no need to use the third rail system for any part of the Eurostar journey. High Speed 1, the tunnel itself and the route to Paris has power provided via overhead catenary at 25 kV 50 Hz. The railways on "classic" lines in Belgium are also electrified by overhead catenaries, but at 3000 V DC.
Track system
The American Sonneville International Corporation track system was chosen, consisting of UIC60 rails on 900A grade resting on microcellular EVA pads, bolted into concrete. The Channel Tunnel network and terminal areas use a very large loading gauge to allow drive-in shuttle rolling stock. Through freight traffic is allowed up to European GC loading gauge if onward travel is via High Speed 1. to either St Pancras (for passenger traffic) or as far as Barking in east London (for freight traffic). Ballasted track was ruled out owing to maintenance constraints and a need for geometric stability.
Source From : http://en.wikipedia.org/wiki/Channel_Tunnel
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