The Battle for a Tunnel
BY AWAKE! CORRESPONDENT IN BRITAIN
“THE project of the Century” is how some view the construction of the tunnel that now links England to Continental Europe.
In this feat of civil engineering, some 15,000 British and French workers joined forces with giant tunnel-boring machines nicknamed Brigitte, Cathérine, Pascaline, Virginie, and Europa. Together they built the world’s longest underwater tunnel below what the British call the Channel and the French, la Manche.* But their success has not been without difficulty and setbacks. Nine men lost their lives during the project.
Many False Starts
“There are few projects against which there exists a deeper and more enduring prejudice than the construction of a railway tunnel between Dover and Calais,” said British statesman Winston Churchill in 1936. When, in 1858, the British Parliament heard a proposal to build a tunnel under the Channel, Lord Palmerston reportedly exclaimed: “What! You pretend to ask us to contribute to a work the object of which is to shorten a distance we already find too short?”
Earlier, in 1802, a French mining engineer, Albert Mathieu-Favier, had proposed to build a lamp-lit tunnel with chimneys rising above the waves to provide ventilation for the horse-drawn carriages. However, the scheme proved to be technically impractical.
In 1856 another Frenchman, engineer Thomé de Gamond, recommended the construction of a railway tunnel to join France and England. The French accepted, but the British were hesitant. Undeterred, de Gamond next consulted with William Low, a British mining engineer. Then, in 1872, Low and fellow engineer Sir John Hawkshaw established a company to raise money for a Channel link. In 1880, boring machines designed by Colonel Beaumont began to tunnel away from Shakespeare Cliff, near Dover, and from Sangatte, on the French coast. After 1,100 yards [1,000 m], work halted when fear of a military invasion frightened the British government off the project.
The next attempt took place in the 1920’s, with a 420-foot [130 m] trial tunnel bored near Folkestone, England. Again British fear of an invasion terminated the work. In the 1970’s tunneling recommenced, only to stop when the British government withdrew support.
Then, 1986 saw the signing of the Channel Tunnel treaty. Ratified the following year by both France and Britain, it permitted work to start in earnest.
The Financial Battle
A group of French and British private companies (known collectively as Eurotunnel) commissioned Transmanche-Link (TML), a consortium of ten construction companies, to design and build the tunnel. At government insistence, private money was to pay for the whole project.
Only two years after work started, Eurotunnel had to revise the financial estimate upward from £5.23 billion to £7 billion. By 1994 the financial forecast for the project had increased to some £10 billion.
The Underground Battle
In reality the Channel Tunnel is not just one but three tunnels. On December 15, 1987, the first TBM (tunnel boring machine) started work in England, and its French counterpart, Brigitte, began on February 28 the following year. Their job was to dig the 15.7-foot [4.8 m]-diameter service tunnel, designed for maintenance and emergency purposes. Larger TBMs ground their way through the rock to open the two main running tunnels, each 25 feet [7.6 m] in diameter when lined.
“At Shakespeare Cliff, we went down a large shaft,” relates Paul, who worked on the tunnel. “When you descended, you got a cold, damp feeling until you reached the bottom, where the air was thick with diesel fumes from all the machinery. As you went through the tunnel, the atmosphere became even more humid and hot.”
Down in the tunnel, a total of 11 TBMs toiled away. Three tunneled landward from Shakespeare Cliff to the site of the British terminal just outside Folkestone. Three more set off seaward under the Channel to meet up with three French ones that started from a shaft at Sangatte. The two remaining TBMs bored the three tunnels inland from there to the terminal at Coquelles, near Calais.
Brigitte operated in one of two modes. When boring through porous, fissured chalk, she worked with both her cutting head and body sealed to withstand water pressure of 156 pounds per square inch [11 kg/sq cm], more than ten times normal atmospheric air pressure. But once out in the chalk marl, a mixture of chalk and clay, she doubled her speed. Then, following this layer between 80 and 130 feet [25-40 m] beneath the seabed, Brigitte pressed on toward her counterpart from the English side.
Like Brigitte, all the TBMs were mobile factories. From the tungsten-carbide-tipped cutting head to the service train at the rear, the largest measured some 285 yards [260 m] in length! Tearing through the rock, cutters rotating two to three times a minute, powered forward by hydraulic piston rams held in place with gripper shoes, one TBM cut through a record 466 yards [426 m] in one week, removed the debris, and lined the hole as well.
Getting It Right
To guide the machine forward, the TBM operator watched computer screens and television monitors. Satellite observations helped plan the exact route in detail before tunneling began. Narrow drills probed the rock face over 160 yards [150 m] ahead, samples of chalk marl indicating the way forward. A laser beam directed at a light-sensitive target on the machine enabled the driver to navigate the correct course.
About four or five miles [6-8 km] out under the Channel, the tunnelers built crossover caverns where trains can be switched from one running tunnel to the other when need arises. Every 410 yards [375 m], hand-tunnelers hewed out passages to link the running and service tunnels.
They also cut out piston relief ducts that join the two main tunnels, in an arc over the service tunnel. “It’s like an old bicycle pump. When you put your thumb over the valve, you can feel the heat,” Paul explains. “The trains generate a lot of heat too. The piston valves open to relieve the pressure and heat of the passing trains.”
Brigitte and her English counterpart halted about a hundred yards [100 m] from each other. Then, very cautiously, a drill forced a 1 1/2-inch [4 cm]-diameter hole through the chalk marl. On December 1, 1990, breakthrough occurred some 13.9 miles [22.3 km] from England and 9.7 miles [15.6 km] from France. Imagine the relief when a final check revealed that the alignment error between the two tunnels was only a few inches [few cm]! The British TBM was then driven on a curve to be left below and to the side of Brigitte. The hand-tunnelers finished the job. Thereafter the running tunnels joined up, and the British TBMs were diverted into underground graves. The French ones were dismantled and removed from the tunnel.
Monotonous but Fast
“There is a very clinical, concrete feel to the tunnel now,” notes Paul. “It’s very monotonous. As you travel through the tunnel, there’s nothing to see except the odd opening where the piston relief ducts and pipes are.” The inauguration was on May 6, 1994, although the public use of the tunnel has been delayed. So, what will it be like?
To find out, you will leave the highway at either Folkestone or Calais, enter the terminal area, pay the fare (from £220 [$330] [U.S.] to £310 [$460] [U.S.] per car depending on the season), drive through customs checks and down the ramp, continue along the platform, and proceed onto the specially designed train, Le Shuttle. Some 35 minutes and 31 miles [50 km] later, you emerge on the other side of the Channel. Drive off the train straight onto the highway—a simple, peaceful passage that allows you to continue your journey quickly. Or stay on the train to London or Paris—with one difference—you will get to Paris at 180 miles per hour [290 km/hr] and to London at 50 miles per hour [80 km/hr]. The Folkestone to London express line will not be ready until 2002!
The battle, however, continues. Disputes persist over the high-speed rail route to link London to the Tunnel. Spare a thought, then, for those relentless TBMs. One of them, on display outside the tunnel exhibition center at Folkestone, bears a sign, “For Sale—One Careful Owner,” yes, ready for another battle!
The Seikan Tunnel linking the islands of Honshu and Hokkaido in Japan is longer (33.5 miles [53.9 km] compared with the Channel Tunnel’s 30.7 miles [49.4 km]), but the underwater stretch is some 9 miles [14 km] less than that of the Channel Tunnel.
[Map on page 15]
(For fully formatted text, see publication)
[Pictures on page 15]
Below: Workers celebrating completion of the world’s longest underwater tunnel
Right: A TBM
Workers: Eurotunnel Ph. DEMAIL; TBM: Eurotunnel