Closer look at the longest and deepest railway tunnel in the world (Video)

A closer look at the longest and deepest railway tunnel in the world, the Gotthard Base Tunnel (GBT) through the Alps in Switzerland, beats the Seikan tunnel in Japan at 35.4 miles (57km) long.

Passenger trains can run through the tunnel at a maximum speed of 155 mph (250km/h).

The control technology for monitoring the tunnel is supplied by world renown Siemens.

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