Progress in tunnel engineering

a) When did people begin tunneling? b) Where were the first tunnels built? c) What were tunnels built for?

Tunneling is difficult, expensive and dangerous engineering work. Tunnels are built to provide direct automobile or railway routes through mountain ranges or under rivers. Before the 19^th century men had not acquired enough skill in engineering to carry out extensive tunneling. Tunnels, however, were known in ancient times. The first-known tunnel was dug in Babylon in about 2180–60 BC. It passed under the Euphrates River and connected the royal palace with a temple. An early Greek tunnel was completed in 687 BC on the island of Samos as part of an aqueduct system.

The Romans built many aqueduct tunnels throughout their vast empire. Their greatest feat was a 3.5-mile (5.6-kilometer) tunnel to drain Lake Fucino in Italy to create Fucino Basin. Few tunnels were built during the next thousand years. The Moors constructed some irrigation tunnels in Spain during the early 1400s, and in about 1450 a project was begun in the Maritime Alps to link Nice and Genoa. This work, however, was never completed.

By the 17th century tunnels were being constructed for use as canals. During the 19th and 20th centuries the development of railroad and, later, motor-vehicle transportation led to a tremendous expansion worldwide in the number of tunnels and in their length.

Early tunnel-building techniques varied. The Egyptians used copper saws that were capable of cutting soft rock, while the Babylonians constructed masonry tunnels. The Romans tunneled through solid rock by heating the rock face with fire and then rapidly cooling it with water, causing the rock to crack. Tunnel building has always been hazardous, and often hundreds or even thousands of workers died constructing ancient tunnels. The development of modern tunneling technology has also included vast improvements in worker safety.

a) When was the first Alpine tunnel built? b) How is it called? c) What new device was used during tunneling for the first time?

Ever since the early days of civilization in Europe the Alps have been a barrier to the movements of people. The first Alpine tunnel to be constructed was the Mont Cenus tunnel. This great project dates back to 1857. This tunnel is of great technical interest because at that time the only way to get through the rock was to use hand tools. At first the construction advanced very slowly. In fact, if it had continued at the initial pace, it would have taken 5 years to complete the tunnel! However, with compressed air drills and dynamite being introduced, progress was accelerated. Work on the Mont Cenus tunnel started in August 1857 and finished in December 1870.

a) What is the name of the second tunnel cut through the Alps? b) What is the length of the tunnel? c) Why was it dangerous to build tunnels at that time?

The next great and extremely difficult task was the construction of the St. Gotthard tunnel. Italian and Swiss engineers started working on this project in 1872. This tunnel 9.3 miles long was completed 9 years later as compared with 14 years required to make the Mont Cenus tunnel. It should be noted that during the period of construction no less then 800 men lost their lives because of poor ventilation. The only means of ventilating was the compressed air exhausted from the drills. It was so insufficient that the death rate among the workers was extremely great. Needless to say that the ventilation ought to have been much better.

a) What is the longest tunnel cut through the Alps? b) What was done to improve ventilation in the course of tunneling? c) Why was a smaller bore (диаметр тоннеля) adopted?

Both the Mont Cenus and the St. Gotthard tunnels are known to be single tunnels. But when it was decided to bore the Simplon tunnel through the Alps, a different scheme was adopted because geological conditions in this part of the mountains were not simple. The planned length of 12.3 miles was greater than had been done before. According to the project two tunnels were cut, side by side, with transverse galleries connecting them at certain intervals. In this way ventilation was greatly improved and the removal of soil was made much easier. Each tunnel could take only one railway track, so a smaller bore was adopted. Had the tunnel been made the same size as the earlier ones, it might never have been completed. These arrangements made the construction much safer.

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