Gotthard Base Tunnel(GBT), the world’s longest and deepest traffic tunnel,is located in which country?

The world’s longest and deepest rail tunnel “Gotthard Base Tunnel (GBT)” has officially begin its regular rail service on December 11, 2016 in Switzerland. The 57 km twin-bore Gotthard base tunnel (GBT) will provide a high-speed rail link under the Swiss Alps between northern and southern Europe. The tunnel has overtaken Japan’s 53.9 km Seikan rail tunnel as the longest in the world and pushed the 50.5km Channel Tunnel linking the UK and France into third place.