In Switzerland, the engineers dug a large 56-km-long tunnel right through the Alps, nothing like no one has ever tried to build. For this work will require the greatest in the world of tunneling machines. The height of each of them more 3-storey building and the length of more 4 football fields! They will be working round the day for 6 years. The success of the construction will allow millions of people to make a more sportive and active travel, but trouble can lead to fire, disaster and destruction.
Daring projects — a series of programs