Tunnels are among the most ambitious civil engineering projects ever undertaken, pushing the limits of geology, ventilation, and construction logistics. The longest tunnels in the world are primarily railway tunnels, which can be bored through mountains or under bodies of water at lengths that would be infeasible for road tunnels due to ventilation constraints.
This list ranks the ten longest tunnels in the world by total length, encompassing both railway and road tunnels. The list is dominated by Swiss, Japanese, and Chinese railway tunnels, which have redefined what is possible in tunnel engineering over the past two decades.
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Length (km)
Length (km)
Gotthard Base Tunnel
57.1 km
Seikan Tunnel
53.9 km
Channel Tunnel (Eurotunnel)
50.5 km
Lötschberg Base Tunnel
34.6 km
New Guanjiao Tunnel
32.6 km
Taihang Tunnel
27.8 km
Hakkōda Tunnel
26.5 km
Iwate-Ichinohe Tunnel
25.8 km
Lærdal Tunnel
24.5 km
Yamato Tunnel
22.2 km
The ranking
1
Gotthard Base Tunnel
The Gotthard Base Tunnel in Switzerland is the longest and deepest railway tunnel in the world at 57.1 km. Opened in 2016 after 17 years of construction, it runs under the Swiss Alps at a maximum depth of 2,300 metres. The tunnel is part of the New Railway Link through the Alps (NRLA) project and carries high-speed passenger and freight trains beneath the Gotthard massif, reducing travel time between Zurich and Milan by roughly an hour.
Country: SwitzerlandType: RailwayOpened: 2016Key feature: Deepest tunnel in the world (2,300 m max depth)
2
Seikan Tunnel
The Seikan Tunnel in Japan is the second-longest tunnel in the world at 53.85 km, and the longest undersea tunnel. It connects the islands of Honshu and Hokkaido beneath the Tsugaru Strait, with a 23.3 km undersea section at a depth of 240 metres below sea level. The tunnel took 17 years to build (1971–1988) and replaced ferry service as the primary rail link between the two islands.
The Channel Tunnel is a 50.45 km rail tunnel connecting Folkestone, England, with Coquelles, France, beneath the English Channel. The undersea section is 37.9 km, the longest in the world. It carries high-speed Eurostar passenger trains, Eurotunnel shuttle trains for vehicles, and freight trains, and has been in operation since 1994. The tunnel consists of three parallel bores: two for rail traffic and one service tunnel.
Country: UK / FranceType: Railway (undersea)Opened: 1994Key feature: Connects UK and mainland Europe; 3-bore design
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4
Lötschberg Base Tunnel
The Lötschberg Base Tunnel in Switzerland is 34.6 km long, making it the fourth-longest tunnel in the world. Completed in 2007, it was the first of the Swiss NRLA base tunnels to open. The tunnel runs beneath the Bernese Alps and carries both passenger and freight trains, with a maximum depth of 2,000 metres. It reduced travel time between Bern and the Valais region by approximately one hour.
Country: SwitzerlandType: RailwayOpened: 2007Key feature: First Swiss NRLA base tunnel to open
5
New Guanjiao Tunnel
The New Guanjiao Tunnel in China stretches 32.6 km through the Guanjiao Mountains in Qinghai Province. Opened in 2014 as part of the Qinghai–Tibet Railway's second line, it is the longest railway tunnel in China and the fifth-longest in the world. The tunnel was built at an average altitude of over 3,300 metres, making it one of the highest-altitude long tunnels ever constructed.
Country: ChinaType: RailwayOpened: 2014Key feature: Highest-altitude long tunnel (~3,300 m average)
6
Taihang Tunnel
The Taihang Tunnel in China is 27.8 km long and is the longest railway tunnel in the Taihang Mountain range. Opened in 2007 as part of the Shijiazhuang–Taiyuan high-speed railway, it was one of the longest tunnels in the world at the time of its completion. The tunnel significantly reduced travel time between Beijing and the Shanxi province.
Country: ChinaType: Railway (high-speed)Opened: 2007Key feature: Part of Beijing–Shanxi HSR corridor
7
Hakkōda Tunnel
The Hakkōda Tunnel in Japan is 26.5 km long and is part of the Tohoku Shinkansen high-speed rail line. It opened in 2010 and was the longest railway tunnel in Japan until the completion of the Yamato Tunnel. The tunnel passes through the Hakkōda mountain range in Aomori Prefecture and was built to withstand the region's heavy snowfall and seismic activity.
Country: JapanType: Railway (Shinkansen)Opened: 2010Key feature: Built in heavy-snowfall, seismic region
8
Iwate-Ichinohe Tunnel
The Iwate-Ichinohe Tunnel in Japan is 25.8 km long and was the world's longest railway tunnel when it opened in 2002, before being superseded by the Lötschberg Base Tunnel in 2007. It is located on the Tohoku Shinkansen line in Iwate Prefecture and was the first tunnel in Japan to exceed 25 km in length.
The Lærdal Tunnel in Norway is the longest road tunnel in the world at 24.5 km. It connects the towns of Lærdal and Aurland in western Norway, eliminating the need for a ferry crossing or a mountain pass that was closed in winter. The tunnel features three mountain halls with coloured lighting to break the monotony and provide visual relief for drivers during the 20-minute journey.
Country: NorwayType: RoadOpened: 2000Key feature: Longest road tunnel in the world
10
Yamato Tunnel
The Yamato Tunnel is a 22.2 km railway tunnel on Japan's Hokkaido Shinkansen high-speed rail line. It was the longest tunnel built specifically for the Hokkaido Shinkansen extension, which opened in 2016. The tunnel was constructed using the New Austrian Tunnelling Method (NATM) and passes through challenging geological conditions in the Oshima mountain range.
Country: JapanType: Railway (Shinkansen)Opened: 2016Key feature: Built for Hokkaido Shinkansen extension
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Full comparison
#
Name
Country
Type
Opened
Key feature
1
Gotthard Base Tunnel
Switzerland
Railway
2016
Deepest tunnel in the world (2,300 m max depth)
2
Seikan Tunnel
Japan
Railway (undersea)
1988
Longest undersea tunnel (23.3 km underwater)
3
Channel Tunnel (Eurotunnel)
UK / France
Railway (undersea)
1994
Connects UK and mainland Europe; 3-bore design
4
Lötschberg Base Tunnel
Switzerland
Railway
2007
First Swiss NRLA base tunnel to open
5
New Guanjiao Tunnel
China
Railway
2014
Highest-altitude long tunnel (~3,300 m average)
6
Taihang Tunnel
China
Railway (high-speed)
2007
Part of Beijing–Shanxi HSR corridor
7
Hakkōda Tunnel
Japan
Railway (Shinkansen)
2010
Built in heavy-snowfall, seismic region
8
Iwate-Ichinohe Tunnel
Japan
Railway (Shinkansen)
2002
World's longest railway tunnel (2002–2007)
9
Lærdal Tunnel
Norway
Road
2000
Longest road tunnel in the world
10
Yamato Tunnel
Japan
Railway (Shinkansen)
2016
Built for Hokkaido Shinkansen extension
How we ranked this
Tunnels are ranked by total length in kilometres, using the most authoritative engineering and operational data available. The primary source for each tunnel is its operator's official documentation, supplemented by structural engineering databases (Structurae) and Wikipedia's list of longest tunnels. Only completed tunnels open to traffic are included; tunnels under construction (such as the Brenner Base Tunnel) are excluded. For railway tunnels, the length includes the full excavated length between portals. The ranking uses the longest continuous tunnel bore, not combined lengths of multi-tunnel systems.
FAQ
What is the longest tunnel in the world?
The Gotthard Base Tunnel in Switzerland is the longest tunnel in the world at 57.1 km, followed by the Seikan Tunnel in Japan (53.85 km) and the Channel Tunnel between the UK and France (50.45 km). All three are railway tunnels.
Why are the longest tunnels all railway tunnels rather than road tunnels?
Railway tunnels can be built much longer than road tunnels because of ventilation constraints. Road tunnels require complex ventilation systems to remove vehicle exhaust fumes, and the cost of ventilation increases exponentially with length. Railway tunnels, especially electric railways, have minimal ventilation requirements, making them feasible at extreme lengths.
What is the longest road tunnel in the world?
The Lærdal Tunnel in Norway is the longest road tunnel at 24.5 km. It features three large mountain halls with coloured lighting to help drivers stay alert during the 20-minute drive through the tunnel.
What is the longest tunnel currently under construction?
The Brenner Base Tunnel, connecting Austria and Italy under the Alps, is under construction and will be 55 km long when completed (expected in the early 2030s). It will be the second-longest railway tunnel in the world after the Gotthard Base Tunnel.