Construction Gotthard Base Tunnel required the excavation of 28.2 million cubic meters of rock, making this project unprecedented in the volume of excavation in the history of engineering. AlpTransit Gotthard AG implemented the excavation of two parallel single-track pipes with a total length of 57.1 kilometers, connecting Erstfeld in the canton of Uri and Bodio in the canton of Ticino. The depth of the route in some areas reaches 2300 meters under the surface of the mountain range, which creates enormous rock pressure on the tunnel lining.
Operation of the facility began in December 2016, when the first regular passenger train passed along the tracks. The infrastructure has reduced travel time between Zurich and Milan by more than an hour, eliminating the need to negotiate steep alpine passes. The design speed of passenger trains is 250 km/h, and freight trains are 160 km/h.
The engineering challenge was not only the length, but also the need to traverse complex geological structures, including fault zones and high temperatures. To ensure safety, advanced ventilation and fire extinguishing systems were introduced, and emergency crossings between pipes were created every 325 meters.
Technical characteristics and record performance
Gotthard Base Tunnel (Gotthard-Basistunnel) is officially recognized as the longest railway tunnel in the world, surpassing the previous record holder - the Seikan Tunnel in Japan. Total length
To ensure passenger safety and personnel, the infrastructure is equipped with sophisticated monitoring systems. The tunnel is equipped with thousands of sensors that monitor vibrations, temperature, concrete deformation and smoke. Motion control system automatically adjusts the intervals between trains, eliminating the human factor.
The tunnel design includes 178 transverse connections between two main pipes, which serve as emergency exits. In the middle of the tunnel there are two multifunctional stations - Sedrun and Fasano, where the train can stop in an emergency or turn around. These stations also play a key role in the organization of ventilation.
⚠️ Attention: In the event of an emergency stop of the train in the tunnel, the system automatically cuts off the access of oxygen to the fire zone and starts powerful fans to remove smoke in a safe direction.
Geology and construction difficulties
The excavation was carried out from five different fronts, requiring the coordination of thousands of workers and engineers simultaneously. Geological conditions varied from hard granites to soft sedimentary rocks and tectonic fault zones. In some areas, the rock temperature reached 46 degrees Celsius, which required constant cooling of the face.
Used for penetration tunnel boring complexes (TPK) and classical drilling and blasting operations. The choice of method depended on the type of rock. Where unstable soils were encountered, preliminary strengthening and injection of concrete were used. Rock pressure at certain points reached 1300 bar, which created the risk of sudden rock outbursts.
Particularly difficult was the Sedrun fault zone, where the geological structure was extremely unstable. Engineers had to develop unique methods of securing the vault to prevent collapse. Despite all the difficulties, none of the main pipes were broken by water from underground sources, which is a rare case for such a scale.
Comparison with other largest tunnels in the world
Although the Gotthard Base Tunnel is the leader in terms of length, there are several other outstanding engineering structures in the world that are also worthy of attention. Each of them solved their own unique problems, be it connecting islands or passing under water obstacles.
Below is a table comparing the main parameters of the largest railway tunnels:
| Tunnel name | Country | Length (km) | Opening year |
|---|---|---|---|
| Gotthard basis | Switzerland | 57,1 | 2016 |
| Seikan | Japan | 53,9 | 1988 |
| Eurotunnel | UK/France | 50,5 | 1994 |
| Lötschberg | Switzerland | 34,6 | 2007 |
Japanese Seikan tunnel, which lost first place, is notable for the fact that a significant part of it passes under the seabed. The Eurotunnel, connecting England and France, remains the most important transport artery in Europe, despite its shorter length. Lötschberg Tunnel, also located in Switzerland, became Gotthard's predecessor and allowed many technologies to be developed.
Why Switzerland?
Switzerland is investing huge amounts of money in railway infrastructure to transfer freight traffic from roads to rails, thus protecting the Alpine ecology from exhaust fumes from trucks.
Economic and environmental significance
The commissioning of the longest railway tunnel has made it possible to radically change logistics in the center of Europe. Freight trains can now travel through the Alps without the weight and size restrictions that existed on the old mountain routes. This reduced the load on highways and reduced the amount of harmful emissions.
Passenger traffic has also reached a new level. High speed trains InterCity and EuroCity provide comfortable and fast communication between northern and southern Europe. Travel times have decreased, making rail travel more competitive with aviation over medium distances.
⚠️ Attention: Using the tunnel requires strict adherence to the rules for the transportation of dangerous goods. Special trains with chemicals pass through the tunnel only when accompanied by a locomotive with a crew and at intervals.
Security and ventilation systems
Safety in such a long underground structure is the number one priority. Installed in the tunnel fire extinguishing systems, which can supply water directly to the fire zone. Special firefighting trains are based at stations on both sides of the Alps and are ready for immediate departure.
Ventilation is provided through shafts in Sedrun and Fasano. In normal mode, the air is renewed naturally due to the movement of trains (piston effect). In the event of a fire, the system goes into overpressure mode, pushing smoke in a specific direction so that passengers can evacuate to a safe area.
☑️ Tunnel safety criteria
Communication inside the tunnel is provided by a radio system GSM-R, which works smoothly throughout. Drivers are in constant contact with the control center. Video surveillance covers all key points, including stations and connection points.
The future of railways
The success of the Gotthard Base Tunnel gave impetus to the planning of new large-scale projects around the world. Engineers are considering building even longer crossings, such as across the Strait of Gibraltar or between the mainland and islands in Asia. Technologies developed in Switzerland become industry standards.
Development of high-speed highways (HSR) is impossible without creating straight sections of track free of steep slopes. Base tunnels running at the base of mountain ranges make it possible to maintain a minimum track slope, which is critical for accelerating heavy trains to high speeds.
Did you know that more than 4 million cubic meters of concrete were required to concrete the tunnel roof? This volume would be enough to build eight Burj Khalifas.
The introduction of automated control systems and smart sensors will make it possible in the future to increase the tunnel's capacity without building new tracks. Digitalization of infrastructure is the next step in the evolution of railway transport.
The main conclusion: the Gotthard Tunnel proved that even the most complex natural barriers can be overcome with the availability of technology and international cooperation.
What is the maximum speed of trains in the Gotthard Tunnel?
The design speed for passenger trains is 250 km/h, however the actual speed may vary depending on the type of rolling stock and timetable. Freight trains travel at speeds of up to 160 km/h.
How long did it take to build the tunnel?
The active construction phase lasted 17 years, from 1999 to 2016. Preparation and geological exploration work began much earlier, back in the 1990s.
Are there any stops for passengers in the tunnel?
Passenger trains do not stop inside the tunnel. The stations of Sedrun and Fasano are technical and emergency; they are not intended for boarding or disembarking people as usual.
Is it possible to drive through the tunnel by car?
No, the Gotthard Base Tunnel is intended exclusively for rail transport. For cars there is a parallel Gotthard road tunnel, which is much shorter and runs higher.
How does the tunnel affect the ecology of the Alps?
The tunnel allows thousands of freight movements to be switched from cars to electrified railways, significantly reducing CO2 emissions and noise levels in sensitive Alpine valleys.