Alpine tunnels: The longest and most important structures

If you want to travel overland from Central Europe to Italy or ski in the high mountains, you have to cross the Alps, where many peaks rise over 4,000 metres into the sky. To shorten the long journeys over these mountains, people in the region began digging through the rock massifs over 100 years ago. As a result, many hundreds of Alpine tunnels have been built to date, shortening journey times by hours in some cases, both by rail and by road. SnowTrex shows where these impressive structures are located and what records some of them hold.

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In Austria alone, there are a total of 166 road tunnels and 29 railway tunnels longer than 1.5 km

History of the Alpine tunnels

For centuries, the Alps have been one of the biggest natural obstacles to the transit of people and trade in Europe. Louis II of Saluzzo also recognised this. This is why the margrave financed a project in 1479 that was unique in the high mountains at the time. He had a tunnel built to speed up the transport of goods on the Via del Sale between Provence and the Po Valley. It took just under a year to complete the Buco di Viso before the approximately 75-metre-long breakthrough in the Cottian Alps on the border between Italy and France near the eponymous Monte Viso (3,841 m) was completed. The work of the labourers, who cut their way through the rock at an altitude of 2,882 m using only pickaxes, can still be enjoyed by hikers today.

Thanks to technical progress, tunnelling in the Alps became easier and easier, but also increasingly dangerous. For centuries, planners relied on black powder to blast their way through the mountains. After hundreds of smaller tunnels had gradually been built in the Alps, ever larger solutions were needed in the 19th century due to the growing volume of traffic and trade. The Col-de-Tende between France and Italy was opened in 1882. In the 21st century, it is still considered the oldest road tunnel in the Alps that can be travelled through. At 3,182 metres, it was the longest structure of its kind in the region until 1964. However, the engineers from both countries were already thinking in completely different dimensions in 1871. Especially when it came to the size of the tunnels in the high mountains. Just under 130 kilometres south of the Col-de-Tende, the Simplon Tunnel (see below) was opened.

Important Alpine tunnels in Switzerland

Gotthard Base Tunnel

If you look at the figures relating to the construction of the Gotthard Base Tunnel, you can roughly imagine how big the project really was in the end. With a distance of up to 2,450 metres, the two 57.1 km long concrete tubes lie almost as far below the peaks of the Gotthard massif as the world’s deepest mines. This means that the project of the century not only holds the world record for the longest railway tunnel, but also for the deepest. During the 17-year construction phase between 1999 and 2016, 2,000 workers from all over the world removed almost 31 million tonnes of overburden from the mountain. This is roughly equivalent to the rock volume of the top 200 metres of the Matterhorn.

On their way through the Alpine massif, the four tunnel boring machines (TBMs), which were guided with millimetre precision by satellites, had to drill through 73 different types of rock. Because the rock was sometimes as hard as granite or as porous as sugar, the maximum distance that each of the 400 m long and 3,000 tonne TBMs could drill per day was 25 to 30 m.

The reason for the construction of the Gotthard Base Tunnel was not only the growing interest of tourists but also the huge volume of freight. The latter in particular had pushed the existing infrastructure, which was designed for the traffic of the 1960s, to its limits. in 2013, the Gotthard road tunnel in particular (see below) was stretched to its maximum capacity for the first time in its history. And the old Gotthard railway tunnel, built in 1882 and over 15 kilometres long, is still important for rail traffic in Europe in the 21st century. However, trains have to adjust their speed on the winding railway line and lose time accordingly.

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Göschenen station is located just a few metres before the 15,003 m long Gotthard tunnel. One of the most famous and important transport structures in Switzerland

The Gotthard Base Tunnel, with its almost non-existent gradient and its two almost dead-straight tubes, was designed to make this journey easier. The capacity of the tunnel in both directions is just under 260 trains per day. Two thirds of these are goods trains, which are allowed to travel through the tunnel at speeds of up to 160 kilometres per hour. In total, they transport 40 million tonnes of freight on the route every year. For ski tourists and other passengers on passenger trains travelling at speeds of up to 250 km/h, the journey through the construction of the century takes just under 20 minutes. The result: the journey time between Milan and Zurich will be reduced by 35 minutes.

The following film shows the technology used in the Gotthard Base Tunnel, how the operators ensure safety and what passengers can (not) see on their journey through the tunnel:

Gotthard road tunnel

In addition to the railway tunnel, another structure was bored through the Gotthard massif in the 1970s. And this was also a record-breaker: the Gotthard road tunnel. At 16.9 kilometres, it is also the longest Alpine tunnel of its kind. It took a total of ten years to complete the single tube between Göschenen in the canton of Uri and Airolo in the canton of Ticino. As part of the A2 national road, the Gotthard tunnel is still one of the centrepieces of the most important motorway route through Switzerland. The majority of daily traffic, around 85 per cent, is actually made up of cars. To ensure safety in the tunnel itself, a speed limit of 80 km/h and a strict overtaking ban apply to all vehicles.

The passage of lorries is also restricted by a so-called “drop counter system”. Since 2002, traffic lights at the two gates have ensured that only around two to three lorries can enter per minute. This makes it possible to limit traffic in the single-lane tunnel, in which it is up to 35 degrees even in winter, to an average of 17,000 vehicles per day.

Construction of the project began on 5 May 1970. In addition to the sheer length of the tunnel, the workers had to contend with two particular challenges. Firstly, the nature of the rock, which forced the engineers to adapt the respective technology for tunnelling through the mountain. And the second major point that had to be taken into account during construction was actually the Gotthard railway tunnel. Both the railway tunnel, which opened in 1882, and the road tunnel begin in the north in the small town of Göschenen. For the construction of the new tube, this meant that the tunnel route led directly under the old structure after just one kilometre. Accordingly, the workers were only allowed to use weak explosive charges for tunnelling. This prevented damage to the old Gotthard tunnel, in which trains continued to run throughout the construction period.

And it is precisely this procedure that will have to be followed in the future, as construction continues on the Gotthard. The reason for this is the age of the existing tunnel. After more than 50 years of operation, the important Alpine tunnel needs to be renovated as soon as possible. This would actually require a month-long full closure of the A2 motorway. However, to prevent total traffic chaos, the builders are taking a different, almost foolhardy approach. The rescue tunnel, which has run parallel to the tunnel itself since the 1970s, is being converted into a second main traffic tube at a cost of almost 2.1 billion euros. Work on the two tunnel boring machines will begin in 2024, and from 2032, cars and lorries should be able to drive through the Gotthard in one lane in each of the two tubes.

In a video clip, the clients of the Swiss Confederation show exactly what the plans for the construction of the second tube of the Gotthard road tunnel look like:

Prices: Travelling through the Gotthard road tunnel is free of charge. There is no toll. However, as is usual in Switzerland, a valid motorway tax sticker is required to use the A2 national road.

Lötschberg Base Tunnel

There are two railway lines in Switzerland that are essential for passenger and goods transport in Europe. One is the Gotthard axis and the other is the Lötschberg-Simplon axis. The second route has included the Lötschberg Base Tunnel since 2007. With a length of 34.6 km, the structure is the fifth longest railway tunnel in the world and therefore also one of the most important Alpine tunnels. Unlike the Gotthard Base Tunnel, the tube between Frutigen in the Bernese Oberland and Raron in Valais is only partially double-track. For winter sports enthusiasts, this means that they can use around 50 passenger trains a day to travel by train to popular ski resorts in Valais, such as Zermatt, Veysonnaz or Zinal. Trains with passengers on board are allowed to rush through the Lötschberg Base Tunnel at speeds of up to 200 kilometres per hour. Goods trains, on the other hand, have to reduce their speed significantly.

In order to increase the capacity of the large structure, the tunnel is to be gradually extended by a second tube. This was already partially built during the construction work, which began on 5 July 1999 and cost over 4 billion euros. However, due to financing problems, the construction of the last 7 kilometres was put on hold for the time being. To this end, the clients only had two tracks laid in the entire tunnel over a distance of 13 kilometres. Despite this, an incredible 16.6 million tonnes of rock were blasted or drilled out of the mountain. The total length of the tunnels under the mountain is 88 kilometres. As with other projects of this kind, most of the excavated material was recycled and, in the case of the Lötschberg, as much as 40 per cent of it was mixed into the concrete to be used.

When the expansion of the second tube of the Lötschberg Base Tunnel will continue depends on the award of the contract by the Swiss parliament. However, the builders hope that work will continue by 2026 at the latest. This would allow them to double the train capacity once the project is completed.

Simplon tunnel

The Simplon Tunnel shows that tube structures literally connect. Passengers travelling by train into the north portal in Brig in Switzerland arrive at Iselle di Trasquera station after 19.8 km, shortly after the south portal. And this is in the Italian region of Piedmont. 24 years after the opening of the first Gotthard tunnel, the first of two tubes in the Rohnetal valley was also opened to rail traffic on 6 May 1906. With a length of almost 20 kilometres, the Simplon Tunnel was not only the longest Alpine tunnel for almost 80 years. Until 1982, when the Dai-Shimizu Tunnel (22.2 km) was opened in Japan, it was also the world’s longest tunnel.

In the 21st century, the Simplon Tunnel is still one of the most important structures for transit traffic through the Alps. Initially, the tunnel was used by passenger trains as well as freight traffic. This included the Simplon-Orient-Express, which replaced the world-famous Orient Express on the Paris-Venice-Istanbul route in 1920, until 1962. In 1956, two car loading stations were finally put into operation at both ends of the tunnel. Winter sports enthusiasts and other tourists who want to save themselves the journey over the winding Simplon Pass can still use this service today. A journey through the tunnel, which was extensively renovated between 2011 and 2015 at a cost of almost 180 million euros, takes just under 20 minutes.

It took seven years to build the first tube (1898 to 1905). And the second was only completed in nine (1912 to 1921). However, the work was not carried out by a company from Switzerland, but by the Hamburg construction company “Brandt & Brandau”. On average, up to 3,000 people a day worked on the construction site under extremely difficult conditions. Because the tunnel was more than 2,100 metres underground in places, temperatures in the mountain reached up to 42 degrees. In order to supply the workers with fresh outside air, those responsible had another tunnel dug at the same time. This was located 17 metres next to the tunnel and was later expanded into the second main tunnel.

The precision with which the men had worked was clearly demonstrated when they broke through the centre of the tunnel on 24 February 1905. Using the technology of the time, they had actually managed to fight their way through the mountain from both sides for almost 10 kilometres and in the end only deviated 20.2 cm to the side and 8.7 cm upwards from the predicted meeting point!

Prizes: A single journey on the car loading train through the Simplon Tunnel costs 26 euros for car drivers. The same price must also be paid by owners of motorhomes under 3.5 tonnes. Smaller caravans (under 750 kg) cost around 15 euros extra, while larger trailers (750 kg to 3.5 tonnes) also cost 26 euros.

Important Alpine tunnels in Austria

Arlberg tunnel

Every winter sports enthusiast travelling by car from Lake Constance to ski in Vorarlberg or Tyrol is sure to have driven through the Arlberg Tunnel. With 13.9 kilometres of subway, it is not only the longest road tunnel, but also one of the most important Alpine tunnels in Austria. The decision to tunnel under the Arlberg was made in 1973, when the winding pass road, which was repeatedly buried by avalanches in winter, was so busy with traffic that an alternative was absolutely necessary. In addition to lorries, the route was mainly used by ski tourists in their cars on their way to the region’s ski resorts, such as Ski Arlberg.

The Arlberg Tunnel project was realised between 1974 and 1978 and took just under 48 months to complete. The construction costs totalled around 977 million euros. The breakthrough in the middle of the tunnel took place on 9 October 1977, before the almost 14 km long structure was opened to traffic on 1 December 1978. Originally, the planners had actually planned two tubes, 70 metres apart, each with two lanes. In the end, however, only the planned southern tube was built, which is used by an average of over 8,000 vehicles every day. One lane is available for traffic in each direction. Cars, lorries and motorbikes are only allowed to travel at a maximum speed of 80 km/h in the tunnel. There is also a strict overtaking ban.

After the two fire disasters in the Mont Blanc Tunnel and the Tauern Tunnel in the early 2000s, the safety precautions in the Arlberg Tunnel were also significantly increased once again. By 2008, six connecting tunnels with a length of between 150 and 300 metres had been added to the Arlberg railway tunnel. Today, they are all declared as official escape routes. A seventh tunnel leads to the Wolfsgruben tunnel, which finally leads out into the open in St. Anton. Operations in the tunnel are monitored 24 hours a day with the help of 43 surveillance cameras. Before entering the tunnel, lorries have to pass through two thermal scanners in front of the two portals in St. Jakob and Langen. If the devices detect overheated parts on a lorry, it is moved to an outdoor parking area for inspection.

Prizes: If you want to drive through the Arlberg tunnel, you have to pay a toll. For both car and lorry drivers, a single journey costs 11.50 euros per vehicle.

Tauern Tunnel

The Tauern motorway, or simply the A10, is one of the most important traffic arteries in Austria. Accordingly, one of the centrepieces on the Salzburg-Villach route is the Tauern Tunnel. With an average of 22,000 vehicles per day, the facility is three times as busy as the Arlberg Tunnel. Planning for the major project, a 44 km long motorway section between Eben im Pongau and St. Michael im Lungau – including the Tauern Tunnel (6,546 m long) and the Katschberg Tunnel (5,898 m long), began in the late 1960s. The two motorway tunnels were actually supposed to consist of two tubes with two lanes each. However, as the construction costs threatened to skyrocket and those responsible expected less traffic, only one tube was built between 1971 and 1975. The plans for the second were initially cancelled completely in 1988.

However, after a fatal fire broke out in the Tauern Tunnel on 29 May 1999, planning for the extension of the tunnel was resumed. The tunnel itself had to be completely closed for three months after the incident. During this time, the tunnel was completely renovated. The renovation, including the new safety precautions, cost a total of 28 million euros. Today, a memorial plaque at the motorway chapel in Flachau commemorates the twelve victims of the fire. More than 30 years after the completion of the first tube, construction of the second tunnel section finally began in July 2006. In the end, the project cost 197 million euros.

The second tube was finally opened to traffic on 30 June 2011. Ski tourists can now reach the huge Ski amadé ski region in Salzburger Land much faster and more comfortably via the Tauern motorway, which now has two lanes in both directions. The ski resorts of Altenmarkt, St. Johann im Pongau and Wagrain can be reached from the A10 motorway in just a few minutes.

Prices: Use of the Tauern Tunnel is subject to a toll. A single journey costs 13.50 euros and entitles you to use the entire A10 motorway.

Plabutsch Tunnel

Unlike the Arlberg Tunnel or the Tauern Tunnel, the Plabutsch Tunnel is not located under a large mountain pass or a mountain. Instead, the almost 10 km long double tube runs through a hilly landscape near Graz. Despite this less spectacular location in the west of Austria’s second-largest city, the Alpine tunnel is of great importance. After all, the structure is part of the A9 motorway and is therefore part of the important traffic artery that connects Upper Austria directly with Styria and the Slovenian border. On average, 30,000 vehicles travel through the Plabutschtunnel every day, and at peak times as many as 41,000.

Similar to the construction of the Tauern Tunnel, only one of the two planned tubes was initially built for the Plabutsch Tunnel. The reason for the entire project was the planned route of the A9 motorway through Graz’s fifth largest district, Eggenberg, in the 1970s. However, following protests from local residents, politicians ultimately decided in favour of a tunnel solution. Construction of the east tunnel ultimately took seven years (1980 to 1987) and cost the equivalent of 160 million euros. The twin tunnel was then completed in 2004, when the west tunnel (construction costs: 142 million euros) went into operation five years after the ground-breaking ceremony.

Following extensive refurbishment (2017 to 2019), the Plabutsch Tunnel is now considered one of the safest structures of its kind in Europe. Part of the safety concept is also speed monitoring through “Section Control”. Instead of “flashing” a vehicle at a specific point if it exceeds the specified maximum speed of 100 km/h, the system works differently. The time between the entry and exit of each car or lorry is recorded before the average speed is calculated in fractions of a second. And if this is significantly higher than the permitted limit, the vehicle owner is sent a fine notice home after a few days.

Prices: Unlike the Tauern and Arlberg tunnels, travelling through the Plabutsch tunnel is free of charge. However, as on all motorways and dual carriageways in Austria, a toll sticker is compulsory on the A9.

Important Alpine tunnels in France and Italy

Mont Blanc Tunnel

The plan to connect the two countries of France and Italy with a road and tunnel under the highest mountain in Europe was set out in writing in an agreement over 70 years ago. However, it took another ten years before the first bore was drilled in what would later become the Mont Blanc Tunnel. It was not until 1959 that construction work began on the French and Italian sides of the Mont Blanc massif. The two towns of Chamonix in the department of Haute-Savoie and Courmayeur in the Aosta Valley region have theoretically been connected since the breakthrough in the middle of the tunnel in 1962, but the Mont Blanc Tunnel was only opened to traffic on 19 July 1965.

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As the name suggests, the Mont Blanc tunnel is located under the mountain massif, the peak of which (4,810 m) is the highest mountain in Europe

Due to the tunnel’s connection to the winding A40 and A5 motorways, it is not used as frequently as other Alpine tunnels. On average, just under 5,100 vehicles a day are counted at the two toll stations. One reason for this is that the Mont Blanc Tunnel consists of just one tube with only two opposing lanes. The construction of a double tube was planned, but then failed. On the one hand, due to a lack of funding and opposition from local residents. On the other hand, the tunnel has a relatively low traffic volume because it is one of the most strictly monitored tunnels in the world.

The reason for this is the fire disaster on 24 March 1999, when 39 people lost their lives in the tunnel. After the tragedy, the single tube was renovated for almost three years and equipped with state-of-the-art safety technology. Part of this concept is also a strict access regulation into the tunnel, in which a speed limit of 70 kilometres per hour and a strict overtaking ban apply. To ensure the safety distance of 150 metres between individual vehicles, a barrier only allows one vehicle through again after a few seconds. The rules are even stricter for lorries. They are dispatched in blocks of five and then escorted through the entire tunnel tube together by a vehicle from the operating company.

Prices: A single journey through the Mont Blanc Tunnel from the French side costs 51.50 euros for car drivers (52.30 euros from Italy). Motorhome owners, on the other hand, have to pay as much as 68.10 euros (69.30 euros from Italy).

Mont Cenis railway tunnel

No Alpine tunnel is as old as the Mont-Cenis railway tunnel. The single tube was opened on 17 September 1871 and has been considered a technical masterpiece ever since. With a length of 13,657 metres, the structure between France and Italy was the world’s longest tunnel for over eleven years. Until 1882, when the first Gotthard tunnel was opened to rail traffic in Switzerland. Joseph François Medail was the first to envisage a rail link between the present-day ski resorts of Modane (Valfrejus) in Savoy and Bardonecchia in Piedmont.

in 1840, he presented his plans for the tunnel to Charles Albert, then King of Sardinia-Piedmont. However, without success. However, the monarch’s successor, Victor Emmanuel II, finally took an interest in the project again nine years later. And his interest was so great that in 1857 he finally ordered the construction of what was then the construction of the century in the heart of the Alps. The tunnel was intended to help better connect the trade routes from Great Britain to the Mediterranean harbours in Italy. Initially, the builders had planned for the construction work to take 25 years. In retrospect, however, it turned out that it would have taken the workers between 40 and 50 years to complete the tunnel with their hand tools.

In the end, however, the Mont-Cenis Tunnel was opened just 14 years after construction began. This was partly due to an ingenious invention by the lead engineer, Germain Sommeiller. He developed the pneumatic hammer drill, which was used on the construction site from 1861. In combination with a new blasting technique, the speed of construction could ultimately be tripled. On Christmas Day 1870, a breakthrough was made in the middle of the single tunnel before the tunnel was opened in the autumn of the following year on 17 September. The trains themselves initially travelled back and forth between France and Italy using steam locomotives for over 40 years. It was not until 1912 that the Modane-Turin line was electrified for the first time.

Fréjus tunnel

The Fréjus Tunnel is the “little brother” of the Mont-Cenis railway tunnel. After all, with a length of 12,870 metres, it is about 1 km shorter than the oldest major tunnel in the Alps. And what’s more, the two twin tubes run parallel to each other through the same mountain massif, only a few hundred metres apart. The new motorway tunnel between France and Italy was opened in 1980 after a total construction period of six years. The project became necessary because traffic capacity in the neighbouring structure was becoming increasingly scarce.

From 1953, many motorists who had previously always driven over the winding Mont-Cenis Pass, which was just under 30 kilometres away, switched to the railway tunnel. In that year, the operating company had opened two car loading stations in Modane and Bardonecchia. This meant that three different types of railway – freight, passenger and car trains – had to share the two lonely tracks through the mountain. To solve the problem and prevent potential traffic jams on the important railway line through the Alps, construction of the Fréjus Tunnel began in 1974. The closure of the gap between the French A43 motorway and the Italian E70 motorway, which cost almost 300 million euros, meant that car traffic was also discontinued.

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Anyone entering the south portal of the Fréjus Tunnel in Italy by car or lorry will arrive in France after 12.9 km, where the north portal is located.

However, since the turn of the millennium, almost two million cars and lorries have been travelling on the two opposing lanes in the single tube every year, so in 2004 the operators decided to expand the Fréjus Tunnel. work on the second tube therefore began in 2009. Five years later, the drilling teams finally succeeded in breaking through the centre of the planned tunnel, which is due to be opened to traffic in 2023.

Prices: The cost of a one-way journey through the Frejus Tunnel from France is 51.50 euros for car drivers (52.30 euros from Italy). Motorhome owners, on the other hand, have to pay as much as 68.10 euros (69.30 euros from Italy).

FAQs on Alpine tunnels

How many tunnels are there in the Alps?

There are several hundred tunnels in the Alps, varying in length from just under 100 metres to more than 57 km. In Austria alone, there are 166 road tunnels and 29 railway tunnels, each longer than 1.5 km. In Switzerland, the unofficial country of tunnels, there are even 112 road and railway tunnels with a length of 1.9 km or more. Italy lists the number of motorway tunnels in the country at more than 200, although some of these are located outside the Alpine region. The same applies to France, where many tunnels are also part of the Grand Nation’s high-speed railway network or connect the mainland with Great Britain in the form of the Eurotunnel.

Where is the longest tunnel in the Alps?

The longest tunnel in the Alps is the Gotthard Base Tunnel. With a length of 57.1 km, the double tube is also in the record books as the longest railway tunnel in the world. The tunnel between Erstfeld in the canton of Uri and Bodio in the canton of Ticino is part of the Gotthard axis and therefore also a centrepiece of intra-European goods traffic. The tracks under the Gotthard massif are used by both freight and passenger trains.

What is the name of the longest tunnel in the Austrian Alps?

At almost 16 kilometres, the Münster Tunnel is the longest tunnel in the Austrian Alps. the structure, which measures exactly 15,990 metres, was opened to traffic in 2012 as part of the New Lower Inn Valley Railway near Jenbach in the province of Tyrol. On the route between Munich and Innsbruck, passenger trains can travel at speeds of up to 220 km/h through the two concrete tubes.

Where is the longest tunnel in the Swiss Alps located?

Since the Gotthard Base Tunnel was opened in 2016, the structure has been the longest tunnel in the Swiss Alps. However, only trains can use the two world record-breaking tubes. The country’s longest road tunnel is only 18 kilometres away from the north portal of the base tunnel. Since 1980, the Gotthard tunnel between Göschenen and Airolo has been the longest of its kind in Switzerland at 16,942 metres.

What is the name of the longest tunnel in the French Alps?

The longest tunnel in the French Alps begins in the village of Modane in the department of Savoie. The record holder is the Mont-Cenis railway tunnel with a length of 13.7 km. The single tube was opened to railway traffic in 1871. This makes the structure the oldest major tunnel in the Alps to this day.

Where is the longest tunnel in the Italian Alps?

The south portal of the Simplon Tunnel is located just behind the Iselle di Trasquera railway station in Piedmont. At 18.8 kilometres, this makes it the longest tunnel in the Italian Alps. Because the north portals of the two tubes are located in Switzerland, trains have been able to travel between the two countries since 1906.