Longest Tunnels in the World

The top 10 Longest Tunnels in the World are Delaware Aqueduct, Paijanne Water Tunnel, Dahuofang Water Tunnel, Orange–Fish River Tunnel, Bolmen Water Tunnel, Chengdu Metro Line 6, Neelum–Jhelum Hydropower Tunnel, Emisor Oriente Tunnel, Qingdao Metro Line 1, Guangzhou Metro Line 18.

The Delaware Aqueduct is the world’s longest tunnel, measuring 85 miles long and 13.5 feet wide followed by the Paijanne Water Tunnel (74.565 m) and the Dahuofang Water Tunnel (53.015 mi) in Finland and China respectively.

In this article, we will look into the top 10 longest tunnels in the World. We will also discuss the location, type, and features of these longest tunnels.

List of Top 10 Longest Tunnels in the World

The following table lists the World’s longest tunnels in the world.

S. No	Name	Location	Type	Length
Largest tunnels in the world
1	Delaware Aqueduct	New York, United States	Water Supply	137,000 m (85.128 mi)
2	Paijanne Water Tunnel	Southern Finland, Finland	Water Supply	120,000 m (74.565 mi)
3	Dahuofang Water Tunnel	Liaoning, China	Water Supply	85,320 m (53.015 mi)
4	Orange–Fish River Tunnel	South Africa	Water Supply	82,800 m (51.450 mi)
5	Bolmen Water Tunnel	Kronoberg/Scania, Sweden	Water Supply	82,000 m (50.952 mi)
6	Chengdu Metro Line 6	Chengdu, China	Metro	68,223 m (42.392 mi)
7	Neelum–Jhelum Hydropower Tunnel	Muzaffarabad, Azad Kashmir, Pakistan	Hydroelectric	68,000 m (42.253 mi)
8	Emisor Oriente Tunnel	Mexico City, Mexico	Wastewater	62,500 m (38.836 mi)
9	Qingdao Metro Line 1	Qingdao, China	Metro	59,818 m (37.169 mi)
10	Guangzhou Metro Line 18	Guangzhou, China	Metro	58,300 m (36.226 mi)

Longest Tunnel in the World – Delaware Aqueduct (United States)

The Delaware Aqueduct is a 137-kilometer (85-mile) tunnel that carries about half of New York City’s water supply. The aqueduct was constructed between 1939 and 1945, and carries around 1.3 billion US gallons of water per day.

• The aqueduct is 13.5 feet (4.1 meters) wide and reaches a maximum diameter of 19.5 feet (6 meters) in its last 13 miles.
• Located in the northeastern part of the United States, it runs through the states of New York, New Jersey, and Pennsylvania.
• It is the world’s longest continuous tunnel that supply a reliable and substantial water supply to millions of people of the New York.
• The aqueduct delivers drinking water from the Rondout Reservoir in Ulster County, situated in the Catskill Mountains to the Hillview Reservoir in Yonkers.

Second Longest Tunnel in the World – Paijanne Water Tunnel (Finland)

Paijanne Water Tunnel is the second longest tunnel in the world. It is a 120-kilometer long water tunnel in Southern Finland and runs 30–100 meters below the bedrock. The tunnel was constructed between 1973 and 1982 to transport water from Lake Päijänne to the Helsinki metropolitan area. The main purpose of the tunnel is to provide fresh water to the people in the Helsinki metropolitan area.

• The tunnel runs at depth of 30–100 metres (100–330 ft) in the bedrock.
• The tunnel has a cross section of 16 square meters (170 square feet). It is wide enough for a truck to pass through. 
• It allows for a water flow of 10 cubic meters (350 cubic feet) per second. The maximum capacity of the tunnel is 12 m³/s, but the average is a mere 3,3 m³/s.
• It takes around nine days for water to traverse the total length of the tunnel. 
• In the event of a water outage, the tunnel can also be used as an emergency water reserve.

Third Longest Tunnel in the World – Dahuofang Water Tunnel (China)

Dahuofang Water Tunnel is the third longest tunnel in the world located in the Liaoning region of China. The total length of the tunnel is 85.3 km (53 mi) with a diameter of eight meter. Around 60 km (37 mi) of the tunnel is being built by using tunnel boring machines (TBM).

• Dahuofang Water Tunnel is a large reservoir diversion project that will meet the water demand of the Shenyang, Fushun, Liaoyang, Anshan, Panjin, Yingkou, and Dalian cities of China.
• The main purpose of the tunnel is to transport water from high rainfall areas to the dry, heavily industrialized Shenyang region of China.
• As the tunnel had different geology sections, therefore different methods were used for the each sections.
• Construction on the tunnel began in the late 1980s and took more than 30 years to complete.
• It is one of the longest tunnels driven by tunnel boring machines (TBMs).

Fourth Longest Tunnel in the World – Orange–Fish River Tunnel (South Africa)

The Orange–Fish River Tunnel is the fourth longest tunnel in the world located inn the central South Africa. The tunnel is the longest continuous enclosed aqueduct in the southern hemisphere and the second-longest water supply tunnel in the world. It was built between 1966 and 1975 to divert water from the Orange River to the Fish River valley.

• Orange–Fish River Tunnel is the 82.8-kilometre (51.4-mile) long irrigation tunnel with a diameter of 5.35 meters and has a fall of 77 meters.
• The main purpose of the tunnel is to divert water from the Oviston at the Gariep Dam(Norvalspont) to the Fish River valley, located in the arid Eastern Cape Karoo for irrigation, industrial use and for drinking water supply.
• It is a tourist attraction and is open to the public for only a few weeks a year in midwinter when the cloverleaf intake roller-valves at Gariep Dam are closed.

Fifth Longest Tunnel in the World – Bolmen Water Tunnel (Sweden)

Bolmen Water Tunnel is the world’s fifth longest tunnel located in the Kronoberg/Scania province of Sweden. It is a 51-mile (82 km) long water supply tunnel that provides drinking water to about 700,000 people. It was built between the 1970s and 1980s to meet the water supply demand of the growing population of the Sweden.

• The tunnel runs from Lake Bolmen in Kronoberg County to the province of Skane.
• The tunnel has a cross-sectional area of 9 square meters and a diameter of over 3 meters. 
• The tunnel has a capacity of 6 m³/s but only 2 m³/s of water is transported through it.
• The water is transported through the tunnel and discharged at the Ringsjöverket waterworks in Scania, where it is treated.

Sixth Longest Tunnel in the World – Chengdu Metro Line 6 (China)

Chengdu Metro Line 6 is a rapid transit line in Chengdu and is the sixth longest tunnel in the world. It is the second longest metro line in Chengdu and the longest non-branching line in China. Chengdu Metro Line 6 is a 68.223 km (42.4 mi)long rapid transit line that runs from Wangcong Temple to Lanjiagou.

• The line runs northwest–southwest, passing through Jinniu District, Chenghua District, Chengdu High-Tech Industrial Development Zone, and Tianfu District.
• The metro started its operation in 2020 and has 56 metro stations.
• The tunnel is underground and is the longest continuous subway tunnel in the world.
• It is designed for speeds of up to 160 km/h and is electrified at 25kV ac 50Hz.

Seventh Longest Tunnel in the World – Neelum–Jhelum Hydropower Tunnel (Pakistan)

The Neelum–Jhelum Hydropower Tunnel is a 32.5 kilometer long tunnel system located in the Muzaffarabad, Azad Kashmir, Pakistan. The main purpose of the tunnel is to divert the Neelum River water to a power station on the Jhelum River. The tunnel passes 380 m (1,247 ft) below the Jhelum River and through its bend. The tunnel system is made up of single and twin circular and horseshoe-shaped tunnels.

• The tunnel system includes:
  • Twin tunnels: 19.6 kilometers each, with a cross-sectional area of 52–58 square meters
  • Single tunnel: 8.94 kilometers long, with a cross-sectional area of 104 square meters
  • Tailrace tunnel: 3.55 kilometers long, with a cross-sectional area of 99 square meters
  • Diversion tunnel: 0.5 kilometers long
• The tunnel system includes a large, underground power station that is 400 meters below the surface. The cavern is 120 meters long, 56 meters high, and 27 meters wide.
• The Neelum–Jhelum Hydropower Project has an installed capacity of 969 megawatts and generates 5.15 billion units of energy annually.

Eighth Longest Tunnel in the World – Emisor Oriente Tunnel (Mexico)

Emisor Oriente Tunnel is the eight longest tunnel in the world located in the Mexico City, Mexico. It is a 62.1 kilometer long wastewater treatment tunnel and is also known as the Eastern Discharge Tunnel, Eastern Wastewater Tunnel, and East Issuing Tunnel. The tunnel was constructed between 2008 and 2019 and runs at a maximum depth of 200 meters (656 Feet) below ground level.

• It runs from Mexico City to the Atotonilco Wastewater Treatment Plant in Hidalgo state.
• The tunnel is the world’s largest sewage project and will connect to Mexico City’s first major wastewater treatment plant and help alleviate flooding.
• It has a 7 meter internal diameter and can transport up to 150 cubic meters of sewage per second.
• It has 24 inflow ducts at a depth of between 150 meters and 200 meters. 
• It’s the country’s largest infrastructure project and is the answer to more than 100 years of sinking in Mexico City.

Ninth Longest Tunnel in the World – Qingdao Metro Line 1 (China)

Qingdao Metro Line 1 is an underground metro line that runs north-south from the North Railway Station to Dongguozhuang. It is the ninth longest tunnel in the world. It is a rapid transit system that crosses Jiaozhou Bay between Fenghuangdao and Tuandao stations. It started it operation in 2020 and has 41 stations. 

• The line has the longest undersea subway tunnel in China, spanning 8.1 kilometers and reaching a maximum depth of 88 meters.
• The tunnel runs 3.49 kilometers undersea and connects the east and west parts of Qingdao.
• The line has 22 stations, 18 of which are elevated, and has a maximum design speed of 120km/h.
• The Qingdao Metro has six lines in operation.

Tenth Longest Tunnel in the World – Guangzhou Metro Line 18(China)

Guangzhou Metro Line 18 is the world’s tenth largest tunnel in the world. It is a 61.3 km (38.1 mi) express line that runs from Wanqingsha in the Nansha District to Guangzhou East Railway Station. The total tunneling distance is 2,525 meters.

• The line has eight stations, including Hengli, Panyu Square, Nancun Wanbo, Shaxi, Longtan, Modiesha, and Xiancun. 
• The metro train can reach speeds of 160 km/h (99 mph).
• The inner diameter of the tunnel is 12.5 m.
• It started its operation in 2021 and has 8 stations.

Key Points based Longest Tunnels in the World

Longest railway tunnels in the world:

• Gotthard Base Tunnel, Switzerland: 57.1 km, the world’s longest railway tunnel.
• Seikan Tunnel, Japan: 53.85 km, connecting Honshu and Hokkaido islands.
• Channel Tunnel, UK/France: 50.45 km, linking the UK with mainland Europe.

Longest road tunnels in the world:

• Lærdal Tunnel, Norway: 24.51 km, the world’s longest road tunnel.
• Zhongnanshan Tunnel, China: 18 km, one of the longest in Asia.
• Yamate Tunnel, Japan: 18.2 km, part of Tokyo’s expressway network.

Longest underwater tunnels:

• Seikan Tunnel, Japan: Also the longest underwater railway tunnel.
• Channel Tunnel, UK/France: Significant portion underwater, serving both rail and vehicle transport.
• Marmaray Tunnel, Turkey: 13.6 km, part of an undersea rail tunnel in Istanbul.

World tunnel rankings:

• Rankings often consider length, usage (rail, road, or service), and engineering challenges.
• The Gotthard Base Tunnel frequently tops lists due to its length and engineering feats.
• Other factors include depth, construction techniques, and geographical challenges.

Longest train tunnels globally:

• Gotthard Base Tunnel, Switzerland: Sets the standard for long-distance, high-speed rail travel.
• Seikan Tunnel, Japan: Besides its length, notable for its deep undersea section.
• Yulhyeon Tunnel, South Korea: 50.3 km, part of an urban rail network near Seoul.

Summary – Top 10 Longest Tunnels in the World

The world’s 10 longest tunnels cover various purposes and locations. The Delaware Aqueduct serves as a water supply tunnel, while the Paijanne Water Tunnel in Finland plays a crucial role in water distribution. China boasts two significant tunnels on the list: the Chengdu Metro Line 6 and the Qingdao Metro Line 1, both facilitating urban transportation. Meanwhile, the Neelum–Jhelum Hydropower Tunnel in Pakistan contributes to power generation. Emisor Oriente Tunnel in Mexico addresses wastewater management, emphasizing environmental concerns. Guangzhou Metro Line 18 in China completes the list, showcasing the global importance of tunnels in diverse fields, from water management to transportation and infrastructure development.

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FAQs – Top 10 Longest Tunnels in the World

Which is the longest tunnel in Asia?

The Zojila Tunnel is Asia’s longest road tunnel, measuring 14.5 kilometers long. The tunnel will connect the Union Territories of Ladakh and Jammu and Kashmir, and provide year-round connectivity between Srinagar and Leh.

Which country has most tunnels?

China has the most tunnels in the world, with 16,229. Japan has the second-most tunnels, with 10,922.

Which is the world’s longest tunnel above 10000 feet?

The Atal Tunnel, also known as the Rohtang Tunnel, is the world’s longest highway tunnel above 10,000 feet. It is located in the eastern Pir Panjal range of the Himalayas on the Leh-Manali Highway in Himachal Pradesh, India.

Which is the longest underwater tunnel in the world?

The Seikan Tunnel in Japan is the world’s longest undersea tunnel by overall length, at 53.9 kilometers.

Which is the longest rail tunnel in the world?

The Gotthard Base Tunnel in Switzerland is the world’s longest railway tunnel, at 57.09 kilometers (35.5 miles) long.

Which is the longest road tunnel in the world?

The Lærdal Tunnel, also known as Lærdalstunnelen, is the longest road tunnel in the world at 24.5 km (15.23 miles) long. It connects the municipalities of Lærdal and Aurland in Vestland county, Norway.

What is the longest tunnel in the world as of 2024?

The Gotthard Base Tunnel in Switzerland holds the title for the longest tunnel, primarily used for railway transport.

Which country has the most tunnels in the top 10 list?

Switzerland has multiple entries in the top 10 list, known for its extensive use of tunnels to navigate the Alps.

Are there any underwater tunnels in the top 10 longest tunnels?

Yes, the Seikan Tunnel in Japan is one of the longest underwater tunnels in the world, serving both railway and freight purposes.

What is the longest road tunnel in the world?

The Lærdal Tunnel in Norway is the longest road tunnel, stretching over 24 kilometers.

Which is the longest railway tunnel in the world?

The Gotthard Base Tunnel in Switzerland is also the longest railway tunnel, facilitating high-speed train travel.

How many of the top 10 longest tunnels are used for transportation?

All of the top 10 longest tunnels are used for transportation, including railway, road, and mixed-use purposes.

What are the engineering challenges in building long tunnels?

Major challenges include geological issues, ventilation, safety measures, and environmental impact.

Are there any new tunnels that might enter the top 10 list soon?

Ongoing and planned projects, like the Brenner Base Tunnel between Austria and Italy, may soon enter the top 10 list upon completion.

What role do these long tunnels play in global infrastructure?

These tunnels significantly contribute to global infrastructure by enhancing connectivity, reducing travel time, and facilitating trade.

Which continent has the highest number of long tunnels?

Europe, particularly due to its mountainous regions requiring tunnels for efficient transportation.