Interurban Environment
Introduction
Rail, road and navigation tunnels are beeing built for centuries. One of the most - if not the most- ancient tunnel of that type is the Malpas tunnel on the Canal du Midi in France built in 1776.
Of course the development of tunnels has been very active during the XIXth century to accompany the development of the railway industry.
At the beginning the tunnels were relatively short eventhough the construction of Alpine tunnels at the end of the XIXth century shows advance rates which allowed construction of more than 10 km long tunnels. (see history).
Recent technical evolutions lead to increasingly longer tunnels in increasingly inhomogeneous grounds. The construction of the Channel Tunnel between UK and France or the Seikan tunnel in Japan are good examples.
Since the end of the 90's and the development of high speed railway lines, it is now necessary to build base tunnels (at altitude between 600 and 900 m) to replace summit tunnels.
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