The Channel Tunnel

The Seven Wonders of the Modern World

Location:

Strait of Dover, between England and France

History:

Two centuries ago, the idea of a road tunnel was suggested to Napoleon during a brief peace between France and England in 1802. But war soon broke out again: the cartoon left is a joke, showing invading French troops walking under the sea in a road tunnel and flying over in balloons (the channel was first crossed by hot-air balloon in 1785).

Both schemes existed only on paper. They lacked the technology to overcome the problems, and did not have the necessary geological knowledge. They guessed that the chalk of Cap Blanc Nez ran under the sea all the way to the white cliffs of Dover - no-one really knew. They imagined horse-drawn carriages driving down a wood-propped tunnel like mines of the day, lit by candles.

The first steam locomotives hauled passenger trains in the 1820's. By 1850 , steam railways were running most of the way from Paris to Calais, and from London to Dover. Crossing the stormy channel in the small ferries of the day was the part of the journey that most travellers dreaded. Many problems arose and frenchman Thomé de Gamond worked hard to find convincing answers: in 1857 his scheme was widely accepted in England and France. After making many hazardous solo dives to check the sea-bed, he proposed a rail tunnel, bored through the chalk which he believed ran below the sea-bed.

Description:

The Channel Tunnel consists of three parallel tunnels running between the respective portals, or tunnel entrances, at either end. There are two rail tunnels, measuring 7.6 m (25 feet) in diameter and about 30 m (98 feet) apart, which carry trains north-west and south-east. Between the rail tunnels is a service tunnel, 4.8 m (16 feet) in diameter, which is connected by cross-passages to the main tunnels at intervals of approximately 375 m (1,230 feet). The service tunnel, served by narrow rubber-tyred vehicles, gives maintenance workers access to the rail tunnels and provides a route for escape during emergencies.

The two running tunnels are directly linked every 250 m (820 feet) by pressure relief ducts (PRDs) that pass over the top of the service tunnel and do not connect to it. At each portal there is a major facility allowing for trains to disassemble and turn around, including customs, maintenance, and other necessary services. The Channel Tunnel is 31 miles (50 km) long, of which 24 miles (39 km) are undersea. The average depth is 150 feet (45 m) underneath the seabed. It opened for business in late 1994, offering three principal services: a shuttle for vehicles, Eurostar passenger service linking London with Paris and Brussels, and through freight trains.

A journey through the tunnel lasts about 20 minutes; from start to end, a shuttle train journey totals about 35 minutes, including traveling a large loop to turn the train round. Eurostar trains travel considerably slower than their top speed while going through the tunnel (approximately 100 mph or 160 km/h, rather than their maximum of 186mph or 300km/h) fit in with the shuttle trains and avoid problems with heat generated in the tunnels by friction.

At completion, it was estimated that the whole project cost around £10 billion, including a cost overrun of 80 percent. The tunnel has been operating at a significant loss, and shares of the stock that funded the project lost 90% of their value between 1989 and 1998. The company announced a loss of £1.33 billion in 2003 and £570 million in 2004, and has been in constant negotiations with its creditors. In its defense, Eurotunnel cites a lack of use of the infrastructure, an inability to attract business because of high access charges, too much debt which causes a heavy interest payment burden, and a volume of both passenger and freight traffic 38% and 24%, respectively, of that which was forecast.