TRANSPORT

Tunnels for transport exist for centuries.
They have been developed both in urban environment for mass transit transports and in interurban environment mainly to cross mountains both for roads and railways.


The development of transport tunnel is still very active, notably in mass transit specifically in Asian countries, but also in European countries where new techniques both concerning construction and exploitation allow smaller towns to build a metro network.
In interurban environment, long base tunnels trend to replace summit tunnels and many underwater tunnels have been built or are at a project stage.
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