Regular rail service through the world's longest tunnel began on 11th Dec, carrying passengers deep under the Swiss Alps from Zurich to Lugano.
The famed Gotthard Base Tunnel (GBT) had a ceremonial opening in June, attracting European leaders Angela Merkel and Francois Hollande for its maiden ride.
The Swiss national rail service (SBB) had announced that 11th Dec would mark the start of normal commercial traffic through the 57-kilometre (35-mile) GBT.
This took 17 years to build, at a cost of over 12 billion Swiss francs ($11.8 billion, 11.2 billion euros).
Improving connectivity from Rotterdam to Adriatic, the tunnel was largely made possible by technical advances in tunnel-boring machines, which replaced the costly and dangerous blast-and-drill method.
The GBT has surpassed Japan's 53.9-km Seikan tunnel as the world's longest train tunnel.
The 50.5-km Channel Tunnel connecting Britain and France has been pushed into third place.
