It is being called ‘the tunnel of the century’ — a feat of civil engineering built of superlatives.
The Swiss transport minister said the Gotthard Tunnel will be a standard against which all tunnels in the future will be compared.
When it is finished the spectacular project will be the biggest railway tunnel in the world.
Two thousand metres below the Swiss Alps passenger trains will be able to hit 250 kilometres an hour, and freight trains 160.
It is 57 kilometres long and will slice the Zurich to Milan journey time from about four hours at present to just over two and a half.
300 trains are expected to pass through per day.
But it has already taken almost 15 years to get this far.
2,000 workers from ten countries have hewn out 24-million tonnes of mountain rock – that is five times more than the Great Pyramid of Giza in Egypt.
Eight workers have died on the project.
The pride of Swiss engineering is the result of a referendum adopting the Alpine Initiative, a plan that obliged the government to shift trans-Alpine heavy goods off the roads and onto trains.
At 7.5-billion euros the price tag is considerably more than the original budget, an increase put down in part to tighter safety measures and unseen geological problems.
Gotthard is the first flat transalpine rail link. At just 550 metres above sea-level it is considerably lower than the current crossing.
Swiss legislation has already demanded that a stop be put on road building in the Alps, and has set a maximum limit on the number of trucks allowed to cross under their own steam.
But those goals can only be fully achieved once the rail link is completely operational.