Deep Tunnel Projects
Documenting large-scale subterranean transit, utility, and research tunnel engineering projects worldwide โ sourced from public construction records and verified engineering data.
Browse by Country
Select a country to explore documented deep tunnel projects. All entries are sourced from public records.
USA
The Central Artery/Tunnel Project (Big Dig) in Boston remains the most complex urban tunneling project in US history.
Afghanistan
The 2.6km Salang Tunnel is a critical strategic passage through the Hindu Kush mountain range.
Australia
The WestConnex project in Sydney features one of the longest continuous motorway tunnel networks in the world.
Austria
The Brenner Base Tunnel is an 84km rail tunnel currently being excavated beneath the Eastern Alps.
Belgium
The 2.5km Leopold II Tunnel in Brussels is the longest road tunnel in the country.
Bosnia
The Sarajevo Tunnel was a documented 800-meter wartime passage constructed during the 1990s siege โ a historical emergency structure.
Brazil
The Rodovia dos Imigrantes features a complex series of deep tunnels through the Serra do Mar mountains.
Canada
The St. Clair River Tunnel was the first full-size subaqueous tunnel built for rail transport in North America.
China
The 18km Qinling Zhongnanshan Tunnel is among the world's longest double-tube road tunnels through a mountain.
Czech Republic
The Blanka Tunnel Complex in Prague spans 6.4km โ the longest city tunnel in Europe.
Denmark
The Fehmarnbelt Tunnel is currently under construction as the world's longest immersed tunnel at 18km.
Egypt
The Ahmed Hamdi Tunnel provides a strategic road link beneath the Suez Canal connecting Africa and Asia.
England
The 50km Channel Tunnel connects the UK to France via the world's longest undersea rail section.
Finland
The 120km Pรคijรคnne Water Tunnel is the second longest continuous rock tunnel in the world.
France
The Channel Tunnel and Lyon-Turin Base Tunnel represent landmark achievements in cross-border deep tunnel engineering.
Georgia
The Rikoti Tunnel is a vital 1.7km passage along the main highway connecting eastern and western Georgia.
Germany
The Fehmarnbelt Tunnel project represents a major cross-border engineering achievement beneath the Baltic Sea.
Greece
The Egnatia Odos highway includes the 4.6km Driskos Tunnel โ the longest road tunnel in the country.
Hong Kong
The 5km Tuen Mun-Chek Lap Kok Tunnel is the deepest subsea road tunnel in the region.
Hungary
The M0 motorway features several deep-cut tunnels designed to bypass the Budapest metropolitan area.
India
The 9.02km Atal Tunnel is the world's longest highway tunnel located above an altitude of 10,000 feet.
Indonesia
The Jakarta MRT project utilizes deep-bore tunneling to create the nation's first subterranean rail network.
Iran
The Kandovan Tunnel is a high-altitude strategic pass through the Alborz mountains.
Iraq
No documented deep tunnel projects meeting our evidence standards at this time.
Israel
The Carmel Tunnels in Haifa constitute the most significant road tunneling project in the country's history.
Italy
The Brenner Base Tunnel and Lyon-Turin Base Tunnel represent major Alpine rail megaprojects shared with Austria and France respectively.
Japan
The 53.85km Seikan Tunnel is the world's longest tunnel with an undersea segment.
Libya
The Great Man-Made River project includes a vast network of deep-bore pipelines and subterranean water storage infrastructure.
Malaysia
The 9.7km SMART Tunnel is a unique dual-purpose stormwater drainage and motorway project in Kuala Lumpur.
Mexico
The 62km Tunel Emisor Oriente is one of the world's largest wastewater drainage tunnels.
Netherlands
The 6.6km Westerschelde Tunnel is the longest road tunnel in the country passing under the Western Scheldt.
New Zealand
The 2.4km Waterview Tunnel in Auckland is the nation's longest and deepest road tunnel.
North Korea
The Pyongyang Metro is among the world's deepest metro systems with stations reaching 110 meters below surface.
Norway
The Rogfast project will include a 26.7km subsea tunnel set to be the world's longest and deepest road tunnel.
Pakistan
The 68km Neelum-Jhelum Hydroelectric Tunnels are the longest continuous water tunnels in the country.
Philippines
The Metro Manila Subway is currently under construction as the country's first deep-bore rail network.
Poland
The ลwinoujลcie Tunnel connects two islands under the ลwina river โ the first immersed tube tunnel in Poland.
Romania
The Transfฤgฤrฤศan highway includes the 887-meter Bรขlea Tunnel โ the longest road tunnel in the country.
Russia
Moscow Metro features some of the world's deepest stations โ constructed during the Soviet era as dual-purpose civil and military infrastructure.
Saudi Arabia
The Riyadh Metro project involves extensive deep-bore tunneling beneath the capital city.
Serbia
The 2.1km Savac Tunnel is a significant part of the nation's modern highway infrastructure.
South Africa
The Gautrain rail system features 15km of deep tunnels beneath the Johannesburg and Pretoria metro areas.
South Korea
The 50.3km Yulhyeon Tunnel is the third longest railway tunnel in the world.
Spain
The 28.4km Guadarrama Tunnel is a high-speed rail link and the longest tunnel in Spain.
Sweden
The 82km Bolmen Water Tunnel is the world's longest tunnel by distance for water supply.
Switzerland
The 57km Gotthard Base Tunnel is the world's longest and deepest traffic tunnel.
Taiwan
The 12.9km Syueshan Tunnel is the longest road tunnel in Taiwan cutting through the Syueshan Range.
Thailand
The Blue Line Metro features significant deep-bore tunneling beneath the Chao Phraya River in Bangkok.
Turkey
The Eurasia Tunnel is a 5.4km double-deck subsea tunnel connecting Europe and Asia beneath the Bosphorus.
Ukraine
The Kyiv Metro features Arsenalna station โ the deepest metro station in the world at 105.5 meters.
Vietnam
The 6.28km Hai Van Tunnel is the longest road tunnel in Southeast Asia.
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