Tunnel Vision

Two kilometers under the Alps, workers are finishing the longest, deepest railway tunnel in the world.

This story appears in the March 2011 issue of National Geographic magazine.

When the Welsh chronicler Adam of Usk traveled over Switzerland's wild and remote Gotthard Pass by oxcart on his way to Rome in 1402, he was so terrified that he asked his guides to blindfold him so he wouldn't have to look.

He wasn't the first alpine traveler to wish there were another way. For thousands of years, the Alps have been the great barrier to travel and trade on the Continent. To cross them meant a drawn-out, often perilous trip, or at the very least a tough uphill slog.

Not for much longer. For the past nine years, an army of tunnelers has toiled deep in the hard granitic core of the mighty mountain range known as the Gotthard Massif, constructing the world's longest and deepest railway tunnel.

Last October miners burrowing north from the Italian-speaking canton of Ticino met their counterparts who'd been boring south from German-speaking Sedrun to conclude the digging phase of one bore of the double-barreled tunnel—a handshake moment televised live on Swiss TV and broadcast across Europe. In April, the final breakthrough is expected in the second tube.

At 57 kilometers long (35 miles), the Gotthard Base Tunnel will handily outstrip the 50-kilometer (31-mile) Channel Tunnel between England and France and the present record-holder, Japan's 54-kilometer-long (33.6-mile-long) Seikan Tunnel. It will stand alone on the engineering front as well. Where its nearest rivals both pass beneath relatively shallow bodies of water, the Gotthard cuts through the complex basement rocks of a giant, heavily folded mountain range. No one has ever tunneled so deep into a mountain, or to such transforming effect.

When it opens, in 2017, it will render Switzerland, for railroading purposes, as flat as Holland. High-speed passenger trains southbound from Zurich will race along a nearly level course all the way to Milan, booming through the Swiss countryside as fast as 250 kmh (155 mph), flashing in one side of the mountains and popping out the other a few minutes later. It will be as though the Alps didn't exist. Travel time between the cities will drop from nearly four hours to just over two and a half—quicker and more direct than if you flew.

Beating out the airlines isn't why the Swiss are spending $10 billion on the tunnel: They're doing it to shift freight, and to curb the spiraling number of trucks clogging their highways and rumbling through their fragile alpine backyard.

Truck traffic has grown exponentially in the sleek new borderless Europe, especially in the Alps, which straddles the fast-growing economic regions of southern Germany and Italy's industrial north. Quiet, neutral, traditionally aloof Switzerland has become a main trucking crossroads. More than a million trucks a year travel over its passes on winding mountain highways and through alpine road tunnels primarily designed for holiday traffic in the 1960s.

The solution, the Swiss decided, was to boost the capacity of the railways to handle freight. And the best way to do that would be to write the mountains and their famous passes out of the equation: Run a set of tracks straight through the bottom of the mountains and out the other side. With no gradients to climb, trains could haul loads twice as heavy and travel twice as fast as those using the old alpine railways. The Gotthard tunnel alone will be able to handle 40 million tons of cargo a year.

The tunnel begins its journey under the 2,108-meter (6,196-foot) pass in the quiet hamlet of Erstfeld, plunging into a hillside through twin concrete portals. It doesn't come out again until Bodio, more than 57 kilometers (35 miles) away, having crossed one of the Continent's great divides. They speak German when you go into the tunnel; Italian when you come out. A rainy day in the quiet hamlet of Erstfeld is likely to be a sunny one in Bodio, and vice versa.

The tunnel avoids the highest (and weightiest) peaks. Its sinuous path seeks out the most favorable geology and skirts potential groundwater complications with lakes that dot the surface some 2 kilometers (1.2 miles) overhead. Five years and $115 million Swiss francs were spent on fieldwork, drilling, soil samples, and a remote sensing survey to map the massif's nooks and crannies to an accuracy of about ten meters.

Nothing about the Gotthard project is small. In the course of building the tunnel, workers will excavate 25 million tons of rock, enough to fill a freight train stretching from Zurich to New York or, if you're so inclined, to build five life-size replicas of the Great Pyramid. Some of the dross will be dumped in Lake Lucerne to create an offshore nesting area for birds. The better quality stuff will be ground up for concrete to line the passage. In all, some 152 kilometers (94 miles) of tunnel will be dug and lined—two main bores, at 57 kilometers (35 miles) each, plus kilometers of access shafts, emergency escape passages, ventilation ducts, and crossover points, so trains can shift channels when tracks need repair or maintenance.

In keeping with the scale of the enterprise, the machines that do much of the work are huge. The gigantic creeping machine known as "The Worm," which applies the concrete lining to and lays the drainage pipes, is nearly 600 meters (1,970 feet) long. A mere 400 meters (1,310 feet) long but vastly more powerful are four 10-meter (33-foot) diameter Tunnel Boring Machines—TBMs in tunneling parlance. In a typical day each of these 2,700-ton behemoths will gouge from 20 to 25 meters (66 to 82 feet) of solid rock, securing newly dug lengths of tunnel with bolts, shotcrete and steel mesh. Each day they'll consume enough electricity to power 5,000 average suburban homes. Like ships, they have names: Sissi, Heidi, Gabi 1 and Gabi 2.

These girlish monikers, together with a few shrines to St. Barbara, patron saint of miners, represent the distaff side of humanity down here. Of the 2,000 or so miners working on the Gotthard Base Tunnel, none are women.

Over the years the sectors linked up, one by one, and with astonishing precision. When the Gabi 1, burrowing south from Erstfeld, reached Amsteg, in June 2009, it was a mere five millimeters off course.

The current tunnel builders are following in a long history of Swiss engineering achievement at the Gotthard Massif. Back in the 13th century, a medieval stone mason succeeded in throwing an arched span over the fearsome Schöllenen Gorge that guards the approach to the pass, and with it opened a lucrative trade route into Lombardy.

Later generations came to see the sights. By the early 1800s the road had to be widened and a sturdier bridge built to accommodate the horse-and-carriage trade of the Grand Tour. The poet William Wordsworth, who passed through on his way to Italy in 1820, bemoaned the "arbitrary, pitiless, godless wretches who have removed nature's landmarks by cutting roads through Alps…"

Little could he have imagined what was to follow. By 1870 the railway had arrived, bringing modernity in its wake. It was a monumental undertaking that included blasting a tunnel 15 kilometers (9 miles) long through the tough granite shoulder of one of the Continent's mightiest ranges.

That 19th-century tunnel took ten years to dig and cost at least 199 lives. Louis Favre, the brilliant Swiss engineer who built it, died of a stroke while inspecting the work, aged 53, only months before the tunnel was complete. The inaugural train ran through in 1882, passengers sipping champagne as they covered the distance between Milan and Lucerne in ten hours. Within the first year, a quarter of a million people had taken the trip. And still the numbers grew. A century later, in 1980, another tunnel was opened through the pass, this time for automobiles—at 16.9 kilometers (10.5 miles) the world's longest road tunnel at the time. A narrow, two-lane affair, it was never designed for trucks, but they came all the same. Gotthard Pass has always been one of the most direct north-south routes through the Alps.

Only one final stretch of virgin rock remained to be dug on the cold and snowy March afternoon when I accompanied AlpTransit's chief engineer, Heinz Ehrbar, on a site visit. By that time, a mere 2.4 kilometers (1.5 miles) of granite and gneiss separated the miners tunneling south from the ski village of Sedrun from those boring north from Faido.

For Ehrbar, Sedrun was where it all began, fifteen years ago, when he was offered the job of project managing this portion of the tunnel. Although he has since been promoted to chief engineer for the whole project, the sector starting from Sedrun remains special—"Heinz's baby," as one of AlpTransit's surveyors put it—not just for old time's sake, but because this was the toughest stretch, where the geology was the most fickle and complex and the tunnel ran the deepest, up to 2,450 meters (8,038 feet) below the mountaintops.

"I enjoyed it," he confided as we donned safety gear—boots, hardhat, miner's lamp, high-visibility overalls and a knapsack with a half-hour's supply of oxygen. "A TBM is an impressive piece of machinery but sitting in an operator's chair, watching dials, isn't as satisfying as blasting your way through the rock."

And some of it really needed working. There was no hope of driving a TBM through the rock in the Sedrun sector. Every meter had to be won the old-fashioned way, by blasting or excavating with conventional machines and shoring up. One 1,100-meter-long (3,610-foot-long) section of a deformed gneiss known as Kakirit took three years to go through—a rate that would have seen the tunnel as a whole take a century to dig. It was nightmarish stuff for tunneling, buttery soft, prone to collapse, and lacking any structural integrity. To keep the immense weight of the mountain from warping the tunnel out of shape, Ehrbar enlarged the passage, then shored it up with huge constricting steel rings that would give slightly under pressure, slowly easing the walls and ceiling into the desired shape and size.

Just getting to the diggings from Sedrun is an adventure. To reach the bowels of the massif, miners had to burrow into a nearby mountainside, then drill a pair of shafts down 800 meters (2,625 feet)—twice as deep as the Empire State Building is tall—and install lifts, one to carry workers and materials up and down; the other for heavy equipment. Engineers from South Africa's famously deep gold mines were flown in to sink the shafts.

It's an exhilarating ride, a whooshing plunge in a steel cage with dust and wind whipping all around. "Better than taking the stairs though," Ehrbar quipped as we stepped out at the bottom into a hot damp subterranean world. We hung our jackets on iron pegs hammered into the rock and boarded a jolting, squealing narrow-gauge miner's train for the long ride to the excavation front. They were between blasts when we arrived, the bucket loaders scooping up debris in one bore of the tunnel, the blasting team prepping the face of the other, pumping explosives into a hundred drill holes, and wiring up the charges.

In a few hours they'd blast again, and push the passage another three meters deeper. Meanwhile somewhere on the other side of the rock face, about 2.4 kilometers (1.5 miles) away, Sissi and Heidi were clawing ever closer through the rock.

On the way back to the lift, Ehrbar pointed out the section they'd labored over, meter by meter, for those three years. "When this is all finished," he said, "I want to go on a test ride through it. They tested the Lötschberg at 288 kilometers an hour (179 miles an hour). We've got a longer tunnel. I want to speed through here like that."

A swift smooth ride through the Alps in comforting darkness: Adam of Usk would have loved it.