The Channel Tunnel ( ), also known as the Chunnel, is a undersea rail tunnel linking Folkestone, Kent in England with Coquelles near Calais in northern France beneath the English Channel at the Strait of Dover. At its lowest point it is deep. http://www.popularmechanics.com/science/extreme_machines/4217338.html?series=23 It has the longest undersea portion of any tunnel in the world, although Japan's Seikan Tunnel is longer overall at and reaches a depth of .

The tunnel carries high-speed Eurostar passenger trains, Eurotunnel ro-ro vehicle transport and international rail freight trains. In 1996 the American Society of Civil Engineers identified the tunnel as one of the Seven Wonders of the Modern World.

Overview

Ideas for a cross-Channel fixed link existed as early as 1802 but the eventual successful project, organised by Eurotunnel, began construction in 1988, opening in 1994. The cost overran predictions by 80%, and concessionaire Eurotunnel overestimated tunnel traffic and has met financial difficulty. Fires have disrupted operation of the tunnel. Illegal immigrants and asylum seekers had been known in the past to use the tunnel to enter Britain, causing a minor diplomatic row over the siting of the Sangatte refugee camp, which was eventually closed in 2002.

Eleven tunnel boring machines working from both the UK and France cut through chalk marl to construct two rail tunnels and a service tunnel. Rolling stock using the tunnel includes Eurostar passenger trains based on the French TGV and vehicle shuttle wagons that are the largest in the world; the tunnel has its own fleet of service vehicles. The vehicle shuttle terminals are at Cheriton (Part of Folkestone) and Coquelles, and are connected to the British and French motorways.

History

{|class="wikitable" width=40% align=right !colspan=2|Key dates |- | 1802 || Albert Mathieu put forward a cross-Channel tunnel proposal. |- | January 1974 || A UK–France government backed scheme that started in 1974 was cancelled. |- | 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 trains commenced operation. |- | November 1996 || A fire in a lorry shuttle severely damaged the tunnel |- | November 2007 || High Speed 1, linking London to the tunnel, opened. |- | September 2008 || A second lorry fire closes the tunnel, with 32 people evacuated