TL;DR: The story of Swiss tunnel engineering, from the first Gotthard rail tunnel of 1882 to the Gotthard Base Tunnel of 2016 -- the longest railway tunnel in the world at 57.1 kilometers. How Switzerland drilled through the Alps to connect north and south, pioneered the NEAT project (New Railway Link through the Alps), and pushed the boundaries of what is possible underground. A tale of vision, engineering genius, and the very Swiss belief that no mountain is too big to go through.
Audio Guide Overview
| Duration | ~35 minutes |
| Type | Swiss engineering and infrastructure |
| Topics | Gotthard Rail Tunnel (1882), Simplon Tunnel, Loetschberg tunnels, NEAT project, Gotthard Base Tunnel, TBM technology |
| Best Paired With | A ride through the Gotthard Base Tunnel, or a visit to the SBB Visitor Center at Erstfeld |
Chapter 1: The Mountain Problem
[Duration: 4 minutes]
Switzerland has a problem that most countries do not have. The Alps.
The Alpine chain runs east to west across the entire width of the country, dividing German-speaking northern Switzerland from the Italian-speaking Ticino in the south. For most of human history, crossing the Alps meant climbing to passes at 2,000 meters or higher, traversing terrain that was snowbound for six months of the year and dangerous even in summer. The Gotthard Pass, the most important north-south crossing, rises to 2,106 meters and was historically open only from June to October.
This geographic barrier shaped Swiss history, culture, and economics. Northern and southern Switzerland developed as distinct worlds, connected by thin threads of trade and communication that could be severed by a single avalanche. The need to cross the Alps -- reliably, safely, and quickly -- has driven Swiss engineering ambition for over 150 years.
The solution, from the beginning, was to go through rather than over. If you cannot climb the mountain, drill it. This simple idea, pursued with Swiss determination and engineering rigor, produced a sequence of tunnels that are among the most remarkable infrastructure achievements in human history.
The story begins in the 1870s, with a man named Louis Favre and a mountain named the Gotthard.
Chapter 2: The First Gotthard Tunnel -- 1872 to 1882
[Duration: 5 minutes]
The first Gotthard Rail Tunnel was the most ambitious engineering project of the 19th century. When it opened on June 1, 1882, it was the longest tunnel in the world at 15 kilometers, connecting Goeschenen in the canton of Uri on the north side to Airolo in the Ticino on the south.
The project was born of geopolitics as much as geography. In the 1860s, the newly unified states of Italy and Germany both wanted a rail link across the Alps. The existing Mont Cenis Tunnel, opened in 1871 between France and Italy, was controlled by France. Germany and Italy needed an alternative, and the Gotthard route through Switzerland was the logical choice.
Switzerland, Germany, and Italy signed an agreement in 1869 to finance and build the tunnel. The total cost was estimated at 187 million Swiss francs -- an astronomical sum at the time. The Swiss engineer Alfred Escher, founder of the Swiss Federal Railways (SBB) and the Credit Suisse bank, was the political driving force behind the project. Louis Favre, a Genevan contractor, won the construction contract.
The construction was brutal. Working from both ends simultaneously, teams of miners drilled and blasted through the granite core of the Gotthard massif. The technology was primitive by modern standards: pneumatic drills powered by compressed air, dynamite for blasting, and hand-carried wagons to remove the rubble. The tunnel was dug at a rate of about 4 to 5 meters per day from each end.
The conditions were appalling. Temperatures inside the tunnel reached 30 to 34 degrees Celsius due to geothermal heat. The air was thick with rock dust, water seeped from the rock face, and ventilation was minimal. Workers suffered from silicosis, heat exhaustion, and a parasitic disease called ancylostomiasis -- hookworm infection -- that spread through the damp, unsanitary conditions underground.
The human cost was staggering. During the 10 years of construction, approximately 199 workers died from accidents, disease, and exhaustion. Hundreds more were permanently disabled. The workforce was predominantly Italian -- poor laborers from Piedmont and Lombardy who took the dangerous work because it was the best-paying employment available. Working conditions were so bad that the Italian workers went on strike in 1875, demanding better pay, shorter hours, and improved safety measures. The strike was suppressed by Swiss militia, and one worker was killed.
Louis Favre himself did not survive the project. He died of a heart attack inside the tunnel on July 19, 1879, three years before its completion. He was 53 years old.
The breakthrough came on February 29, 1880, when the two bore holes met in the middle of the mountain. The alignment was nearly perfect -- the two bores were off by just 33 centimeters horizontally and 5 centimeters vertically over a distance of 15 kilometers. This was a remarkable feat of 19th-century surveying, achieved with theodolites and mathematical calculations alone, without GPS, lasers, or any of the electronic guidance systems available today.
The tunnel opened to traffic on June 1, 1882, and it transformed European transportation. The journey from Zurich to Milan, which had previously taken days by coach over the pass, could now be completed in hours by train. Trade between northern and southern Europe surged. Tourism to Switzerland boomed. And Switzerland itself was knitted more tightly together, the Alpine barrier pierced for the first time.
Chapter 3: The Simplon and Loetschberg -- Drilling Deeper
[Duration: 4 minutes]
The Gotthard's success inspired more tunnels. The next major project was the Simplon Tunnel, connecting Brig in the Valais to Iselle in Italy, opened in 1906. At 19.8 kilometers, it surpassed the Gotthard as the world's longest tunnel and held that record until 1982.
The Simplon was even more challenging than the Gotthard. The tunnel passed through rock at depths of up to 2,135 meters below the surface -- the deepest point of any tunnel in the world at the time. The geothermal heat was extreme, reaching 56 degrees Celsius in some sections. Engineers had to pump cold water through pipes to keep the working face at tolerable temperatures. Hot springs were encountered that flooded entire sections with scalding water, requiring massive pumping operations. The workers, again predominantly Italian, endured conditions that were, if anything, worse than the Gotthard.
The Simplon was built as two parallel single-track tunnels rather than a single double-track bore. The first tube opened in 1906; the second in 1921. This twin-tube design would prove prophetic -- it became the standard approach for major rail tunnels in the 21st century, including the Gotthard Base Tunnel.
The Loetschberg Tunnel, opened in 1913, connected the Bernese Oberland to the Valais through a 14.6-kilometer bore beneath the Loetschberg massif. Its construction was marked by a catastrophe: on July 24, 1908, miners broke through into a pocket of water-saturated gravel and glacial debris. The resulting inrush of water and rock killed 25 workers and destroyed hundreds of meters of completed tunnel. The affected section had to be abandoned and a new alignment drilled around the obstacle. The disaster demonstrated the geological uncertainties that all tunnel builders face -- no matter how thorough the surveys, the mountain always has surprises.
Together, the Gotthard, Simplon, and Loetschberg tunnels created a rail network that could cross the Alps at three points, providing redundancy and capacity that served Switzerland through two world wars and the economic boom of the postwar decades.
Chapter 4: NEAT -- New Railway Link Through the Alps
[Duration: 5 minutes]
By the 1980s, it was clear that the existing Alpine rail tunnels were reaching their capacity limits. Freight traffic was growing, passenger demand was increasing, and the steep gradients of the 19th-century tunnels -- the Gotthard climbs to 1,151 meters at the tunnel's midpoint -- limited train weights and speeds.
The solution was audacious: drill entirely new tunnels at the base of the mountains, running flat and straight beneath the Alps at valley-floor elevation. This concept, known as NEAT (Neue Eisenbahn-Alpentransversale, or New Railway Link through the Alps), proposed two new base tunnels -- the Gotthard Base Tunnel and the Loetschberg Base Tunnel -- that would create a flat, high-speed rail corridor through the Alps.
The NEAT project was approved by Swiss voters in a 1992 referendum, and its financing was confirmed in a second vote in 1998. The total cost was estimated at 24 billion Swiss francs. The democratic approval is worth noting: the Swiss people voted, twice, to spend billions of francs on a railway infrastructure project that would take decades to complete. This is direct democracy applied to engineering.
The Loetschberg Base Tunnel opened first, in 2007, at 34.6 kilometers. It was the longest land tunnel in the world at the time of its opening (the Seikan Tunnel in Japan is longer but runs partly under the sea). The Loetschberg dramatically reduced travel times between Bern and the Valais, cutting the journey from about two hours to under one.
But the Loetschberg was merely the appetizer. The main course was the Gotthard.
Chapter 5: The Gotthard Base Tunnel -- The Longest in the World
[Duration: 6 minutes]
The Gotthard Base Tunnel, opened on June 1, 2016 -- exactly 134 years after the first Gotthard tunnel -- is the longest railway tunnel in the world at 57.1 kilometers. It runs from Erstfeld in the canton of Uri to Bodio in the Ticino, passing beneath the Alps at a maximum depth of 2,300 meters below the Piz Vatgira above.
The numbers are staggering. The tunnel was under construction for 17 years. It required the excavation of 28.2 million tons of rock -- enough to fill the Great Pyramid of Giza five times over. The tunnel system includes 152 kilometers of shafts, galleries, and passages. The maximum rock temperature encountered during drilling was 46 degrees Celsius. The tunnel consumed 4 million cubic meters of concrete and 300,000 tons of steel.
Four massive tunnel boring machines, or TBMs, did most of the drilling. Each TBM was a self-contained factory on wheels, about 400 meters long and weighing over 3,000 tons. The rotating cutting head, 9.5 meters in diameter, was studded with tungsten carbide disc cutters that ground through the rock at pressures of up to 300 kiloNewtons per cutter. Behind the cutting head, the TBM erected prefabricated concrete lining segments, creating a finished tunnel as it advanced. The machines advanced at rates of up to 30 meters per day, depending on rock conditions.
But TBMs could only be used in the right geological conditions. Where the rock was too fractured, too wet, or too unpredictable, engineers reverted to drill-and-blast methods, the same basic technique used in the 1882 tunnel but with vastly improved explosives, ventilation, and safety systems. About 80 percent of the tunnel was bored by TBM; the remaining 20 percent was drill-and-blast.
The geological challenges were immense. The tunnel passes through at least 73 distinct rock types, from hard Aar granite to soft Piora mulm, a sugar-like rock that crumbles under pressure. The Piora zone, a 200-meter section of tectonically crushed and water-saturated rock, was considered the tunnel's greatest engineering risk. Geologists feared that the Piora mulm would be impossible to tunnel through, potentially halting the entire project. In the event, the zone proved manageable, though it required specialized ground-freezing techniques and careful water management.
The tunnel is designed for speeds up to 250 kilometers per hour, though current operations run at about 200. The journey from Zurich to Lugano, which used to take nearly three hours, now takes just over two. Freight trains can cross the Alps on a flat gradient of no more than 12.5 per mille -- a revolutionary improvement over the old Gotthard line's 26 per mille grade, which limited train weights and required additional locomotives.
Nine workers died during the construction of the Gotthard Base Tunnel. Each death was a tragedy, but the safety record represents a dramatic improvement over the 199 deaths in the first Gotthard tunnel. Modern safety standards, including mandatory hard hats, emergency shelters, ventilation systems, and medical teams on site, have made tunnel construction far safer than in the 19th century, though it remains one of the most dangerous occupations in the construction industry.
The tunnel's opening ceremony on June 1, 2016, was attended by the leaders of Switzerland, Germany, France, and Italy. Regular passenger service began in December 2016. The first full year of operation saw about 42 million tons of freight pass through the tunnel, and the numbers continue to grow.
Chapter 6: The Engineering Legacy
[Duration: 4 minutes]
Swiss tunnel engineering did not develop in isolation. It drew on global expertise and, in turn, influenced tunnel projects worldwide. But the density of tunnel infrastructure in Switzerland is unmatched anywhere on Earth.
Switzerland has over 2,000 road and rail tunnels, totaling more than 600 kilometers of underground passage. The country's rail network includes some of the most technically challenging tunnels ever built, from the spiral tunnels of the Gotthard railway, where the train loops inside the mountain to gain altitude, to the Vereina Tunnel in Graubunden, which allows car trains to cross the Alps in winter when the passes are closed.
The Ceneri Base Tunnel, the final piece of the NEAT project, opened in December 2020 at 15.4 kilometers. Together with the Gotthard Base Tunnel, it creates a continuous flat corridor through the Alps, from the Swiss Mittelland to the Ticino lowlands. Trains can now cross the Alps without a single significant climb, fundamentally changing the economics of north-south European freight transport.
The NEAT project's broader goal is to shift freight from road to rail. Switzerland is the only country in Europe that mandates the transfer of trans-Alpine freight from trucks to trains. The Heavy Vehicle Fee, introduced in 2001, charges trucks for every kilometer driven on Swiss roads, making rail transport economically competitive. The combination of the fee and the new base tunnels aims to reduce trans-Alpine truck traffic from about 1.4 million crossings per year to 650,000 -- an ambitious target that the tunnels are designed to make achievable.
Swiss tunneling expertise is now exported worldwide. Swiss engineering firms have been involved in major tunnel projects across the globe, from the Channel Tunnel between England and France to metro systems in Asia and South America. The Herrenknecht company, while German, has built many of the TBMs used in Swiss tunnels, and the technology developed for the Gotthard and Loetschberg projects has advanced the global state of the art in rock mechanics, tunnel ventilation, and underground rail systems.
The environmental dimension is important. The NEAT tunnels are explicitly designed as climate infrastructure. By shifting freight from road to rail -- where electric trains produce far fewer emissions than diesel trucks -- the tunnels contribute to Switzerland's climate goals. The electricity powering the trains comes largely from Swiss hydroelectric dams, making the trans-Alpine rail corridor one of the lowest-carbon freight routes in Europe.
Conclusion
[Duration: 2 minutes]
The story of Swiss tunnel engineering is, at its core, a story about refusing to accept geographic limitations. Other countries might have looked at the Alps and built their trade routes around them. The Swiss looked at the Alps and drilled through them. Not once, but repeatedly, each time more ambitiously than the last.
From the first Gotthard tunnel of 1882, where Italian miners died by the hundreds in the dark and heat, to the Gotthard Base Tunnel of 2016, where billion-franc boring machines carved through 57 kilometers of rock with centimeter precision, the arc of Swiss tunneling is an arc of technological progress and national determination.
The tunnels are more than infrastructure. They are symbols of Swiss identity -- of the belief that problems can be solved with engineering, that mountains can be moved with patience and skill, that a small country can build things that astonish the world.
The next time you ride a train through the Alps and emerge, minutes later, in a different world -- different language, different climate, different culture -- remember the engineers, the miners, and the voters who made it possible. The mountain did not move. They went through it.
This has been your ch.tours audio guide to Swiss Tunnel Engineering. Safe travels, above and below ground.