Gotthard Base Tunnel (GBT) is the longest train tunnel in the world and it is located in Switzerland.
The tunnel is being constructed beneath the Swiss Alps and is still under construction.
It is scheduled to become operational at the end of 2016.
The length of the tunnel is 57 KM.
Seikan Tunnel in Japan used to be the longest train tunnel; now it is the second longest after Gotthard Base Tunnel.
Here are some REUTERS’s photos of the Gotthard Base Tunnel :




