At 57 km, the Gotthard Base Tunnel will be the longest rail tunnel in the world once it opens for use in mid-2016.
Matthieu Gafsou for TIME
April 9, 2015 10:44 AM EDT

The sky is still black over the Swiss Alps as we climb aboard a train one morning in late March and head inside the mountains. In an instant, the sharp alpine air thickens to a torpid heat reaching nearly 40°C. The temperature rise is a function of geology, not meteorology­—we are deep inside solid rock, in the 57-km-long Gotthard Base Tunnel. More than 1,800 m of mountain is piled above our heads. “This is extremely high-­pressure rock and the water pressure is also very high,” says Renzo Simoni, a Swiss civil engineer and CEO of AlpTransit Gotthard AG, the company that is overseeing one of the world’s most ambitious engineering projects, as he guides us along a dark tunnel track. “Working in these conditions is very, very hard.”

Indeed—building the Gotthard Base Tunnel has taken decades of backbreaking toil by more than 2,600 people, at a cost of more than $10 billion. But after 23 years of work, the result is spectacular. When it finally opens in June next year, the tunnel­ will be the longest in the world, longer than the Seikan Tunnel in northern Japan and the Channel Tunnel connecting England and France.

But it’s not just length that sets Gotthard apart. Unlike those two, which partly travel under water, the Swiss tunnel required drilling through exceedingly hard granite and quartz, under the Gotthard massif in the Alps. Thanks to the 800-m-deep shafts needed to pump in air and drop millions of tons of cement for the tunnel walls and floors, the Gotthard Base Tunnel will not only be the world’s longest but will also have what Simoni believes is the world’s most powerful ventilation system. In order to bore a total of 152 km of tunnels, shafts and passages (there are twin, parallel rail tunnels, one for each direction), the workers cut through 13 million cu m of rock, the volume of nearly nine Empire State Buildings.

An Engineering Dream

All this would have been essentially impossible until the recent development of high-precision boring machines capable of digging a tunnel this long. With shafts nearly a kilometer long, engineers needed satellites to map out the entire route; an error of even a few millimeters would mean redoing entire parts of the tunnel. For environmental reasons, the concrete for the tunnel walls came from the rock the workers excavated, rather than from riverbeds, as is often the case with tunnel building. That meant developing entirely new plastic compounds to seal the walls against possible leaks. “This is completely different,” Simoni said. “This had never been done before.”

But while the technology to build an epic Alps tunnel is new, the dream isn’t. In 1947 the Swiss engineer Carl Eduard Gruner fancifully suggested tunneling through the Alps between the northern city of Basel to Chiasso on Switzerland’s southern border with Italy—a distance of some 285 km—because the cars snaking bumper to bumper over the twisting mountain passes were threatening to turn the bucolic slopes into an endless traffic jam.

Nearly seven decades after Gruner first floated his idea, the traffic in the Swiss Alps is as much a problem as ever. The original Gotthard rail tunnel, about an hour’s drive south of Zurich, is still used, but it was built in the horse-and-buggy era in 1882, is only 15 km long and is too steep and twisting for long modern freight trains to use.

As the container ships that carry international cargo have grown bigger, the container-truck traffic that bears that freight from port to final destination has become heavier. About 1.2 million container trucks barrel through the Swiss Alps every year, leaving politicians and regular citizens wondering whether clouds of diesel fumes might one day choke their country’s iconic landscape. “The Alps are extremely important to the image of Switzerland,” says Manuel Herr­mann, head of transport policy at Alpine Initiatives, an organization set up in 1989 to push the government to restrict truck traffic across the mountains. Herrmann claims the air pollution and noise in the Swiss Alps’ five valleys is now comparable to cities like Paris. That’s more than an environmental danger—it’s a cultural threat to a country whose traditions are rooted in the ideal of clean mountain living. The tunnel opening in Erstfeld is close to the mountain village where William Tell shot an apple off his son’s head with a crossbow, or so the famous legend goes. “You think of Switzerland, you think of the mountains,” says Herrmann.

Modern freight trains need flat tracks, which meant tunneling through deep rock at the heart of the mountains in order to avoid the craggy alpine peaks and crevices. So the Gotthard Base Tunnel sits about 600 m below its 19th century predecessor, with just a slight incline. That will allow freight trains to speed along the tracks at 160 km/h, carrying double the load of the freight trains that now use the old tunnel. For every three freight trains, a passenger train will zip through the tunnel at speeds up to 250 km/h.

Little has been left to chance in the design. Giant doors painted bright yellow seal off emergency tunnels into which trains can move along side tracks in the event of engine problems. The morning we went into the tunnel, a few dozen workers crouched on the tracks, checking bolts and wiring electrical connections, finishing some of the last preparations for six months of test runs beginning in October, before its official opening, planned for June 5 next year.

From the start, the sheer technical dangers of the project weighed on engineers. “The nightmare scenario during excavation was a rockfall or water coming in,” says AlpTransit Gotthard CEO Simoni. (Eight construction workers died over two decades, but from being hit by trains or from falling, rather than accidents specifically relating to the building of the tunnel.) Simoni says one complication engineers faced in constructing the new tunnel was the composition of the Gotthard rock itself, which has a tendency to “squeeze together, as if it’s trying to fill empty spaces.” So the builders installed a series of steel arches to keep the tunnel walls stable. To stop water from seeping in—one of the biggest dangers in the construction of any tunnel—engineers developed custom sealing foils, which sit between two concrete linings, with the outer walls up to 80 cm thick in parts.

More Tunnels, More Traffic

Yet while no one would dispute that the Gotthard Base Tunnel is an engineering marvel, one question remains: Will it actually fulfill the reason for its construction and reduce the huge numbers of trucks crossing the Swiss Alps?

After more than 20 years and $10 billion, the answer is still unclear. One glance at the map of Europe shows the reason why. With just 8 million people, tiny Switzerland is wedged between three industrial giants: Italy to the south, France to the west and Germany to the north. Europe’s major ports of Rotterdam, Hamburg and Antwerp, where millions of container ships off-load Asian and U.S. imports and ship out E.U. exports every year, sit at one end of the continent’s North-South axis, with Switzerland at the heart of this economic circulatory system.

Even though the Gotthard tunnel is all but completed, Switzerland—which is not a member of the E.U.—believes that Europe will need a bigger network of freight rails if the traffic jams in the Alps are to be cleared. But that’s a tough sell for a continent digging out from an economic crisis. It’s even possible that the new tunnel network will increase the number of trucks by expanding the regional freight market, while leaving other countries without high-capacity freight rails, according to a 2013 independent study commissioned by the Federal Office of Transport in Bern.

It sounds counterintuitive, but it’s often true—new roads and rails can end up inducing additional traffic, not relieving it. Alpine Initiatives, the organization that works to reduce truck traffic, believes that Europe instead needs to ration the right to cross the mountain, through what it terms the Alpine Crossing Exchange. Trucking companies would buy and sell a limited number of rights to ship their goods across the mountains. “Trucks are driving through all of Europe,” says Herrmann. “You cannot just build tunnels and expect miracles to happen and road traffic to go away.” The tunnel’s contractor AlpTransit disagrees, hailing Gotthard as a major convenience for both goods and people that will shorten journey times and allow more goods to be shipped while consuming less energy—all key factors in a country that prides itself on clockwork efficiency.

When we emerge from the Gotthard tunnel later that March morning, the sun is high in the sky, glistening off the huge snow-capped peaks, while sheep graze lazily on emerald green farmland along the side of the road. At a rest stop across the freeway, truck drivers pausing for coffee park their vehicles, which show license plates from Lithuania, Serbia, Italy, Germany, the Netherlands and elsewhere. None of them seem aware that they are a short walk from the world’s longest rail tunnel, nor that it is aimed at stopping them from driving their trucks through this storybook landscape. It could be years before that happens, if it ever does. Whatever its ultimate impact, however, the Gotthard Base Tunnel will stand as a monument to Swiss precision and perfectionism­—on a mountainous scale.

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