The Channel Tunnel, informally known as the “Chunnel”, is a train tunnel under the English Channel connecting France and England.  It is the longest underwater train tunnel in the world.  With trains that can travel up to 100 mph, it can go from London to Paris in just three hours.  The Channel Tunnel actually consists of three tunnels: two main tunnels and a smaller service tunnel in between.  23 miles of the tunnel are underwater, and it only takes 35 minutes to cross from one side of the channel to the other.  Construction on the tunnel began at both ends in 1987 and the tunnel opened in 1994, 2 years later than scheduled.  The whole project cost $14 billion, more than double the original projected cost.  It took 7000 workers to finish the project, and 11 men lost their lives during the construction.   

image from http://thebesttraveldestinations.com/the-channel-tunnel-a-tunnel-connecting-britain-and-france/


                The idea of building a tunnel under the English Channel has been around since the early 1800s, but the first serious designs were actually made in the mid 1800s.  From the beginning, the English were afraid that making a land link between the island and France would provide easy access should the French decide to invade.  Therefore, interest in the tunnel varied over the years, depending on relations between England and France.

                Tunnel boring machines were invented in 1875, making the idea of digging a large tunnel more attainable.  Two tunnel companies actually began digging in 1881 from the English and French sides, and after one year, each had bored almost 2 km of tunnel.  They projected that a 7 foot diameter pilot tunnel could be extended across the Channel within 5 years.  The success of this attempt worried the British military about French invasion, so further construction on the tunnel was banned in 1883.

                The idea of building a tunnel persisted, but it was not until 1974 that another attempt was made.  The project was again abandoned, however, due to an economic downturn.  Finally, in 1987, a private company again took on the project, and the tunnel was completed and opened in 1994.


The tunnels were dug out using twelve tunnel boring machines, or TBMs.  These custom-built machines were 800 feet long and weighed 1400 tons.  The 28-foot diameter cutting heads would rotate at 3.5 revolutions per minute, and their clusters of steel teeth could eat away at the rock at a rate of 15 feet per hour.


The Channel Tunnel consists of two 25-foot diameter single-track rail tunnels and a third 16-foot diameter service tunnel in between, serving as an

Public Domain
emergency exit.  The three tunnels are connected every 820 feet by passages to relieve the air pressure built up in front of the trains. 

Only trains travel through the tunnels, but they can carry freight, passengers, and cars.  The train cars used in the tunnel are each a quarter of a mile long, and the trains can travel at up to 100 miles per hour.  Eurotunnel and Eurostar are the main companies that operate the tunnel.

                                                                                                                                 public domain image

Since the completion of the Tunnel, cross-Channel transportation has increased in general, but only about one third of the transport relies on the tunnel.  About one half of car movements across the Channel use the Tunnel.  This is a contributing factor to the continued financial struggle of the Tunnel operators.  The ferry sector that controlled most cross-Channel transportation before the completion of the Tunnel was expected to be severely hurt by the Tunnel.  However, the ferry sector successfully responded to the competition and continues to have service similar to that of the 1980s.  The Tunnel has shifted more cross-Channel traffic to Dover and Calais and away from other locations.

The tunnel has made it possible for people to make day trips to France or England, something unheard of before the Tunnel was completed.  Many go to shop for certain goods that are cheaper in the other country.  A popular trip for the English is to go to France to buy wine at prices lower than those in England.  It was hoped that the Tunnel would contribute to a significant expansion of tourism and employment in the areas surrounding it, but there is little evidence that this has occurred. 

For more information: http://www.theotherside.co.uk/tm-heritage/background/tunnel.htm

History Channel: Modern Marvels The Chunnel Video