At 57 km long, the Gotthard Base Tunnel is the longest and deepest tunnel in the world. Every day, 2,000 workers descend into the Swiss Alps, braving the heat and dust to continue work on the mammoth engineering project. Their mission is to solve the biggest traffic congestion problem in Europe. It is hoped that when it is completed, the tunnel will revolutionise transport across the Alps. From 2017, high-speed trains will be able to make the trip faster than an aeroplane. However, this daunting project would not be possible without six innovations. (thetvdb.com)