The Top 9 Longest Tunnels in the World

Tunnels are some of the greatest engineering feats humanity has ever undertaken. We (humankind) have, in fact, been digging them for millennia.

But, they have not all been excavated for purely logistical reasons. Tunnels were, and still are, widely used for mining operations and were commonly used in warfare.  

Predecessors of modern tunnels were called adits that were built to transport water for irrigation or drinking and sewerage. The first Qanats, early underground aqueducts, have been from well before 2000 B.C.

In the following article, we'll take a look at the 9 longest tunnels in the world. 

RELATED: 5 MOST CHALLENGING TUNNEL CONSTRUCTIONS AROUND THE WORLD

In which country will you find the world's longest road tunnel?

The longest road tunnel in the world is the Lærdalstunnelen in Norway. It runs for a total of around 24.5 km and was built between 1995 and the year 2000.

How long is the longest underwater tunnel?

Whilst it didn't make the list below, the longest underwater tunnel is Channel Tunnel (Eurotunnel) that runs between Folkestone in England and Pas-de-Calais in France. This tunnel was the second longest railway tunnel in the world for a time.

It still retains the title for the longest underwater tunnel and the longest international tunnel. The tunnel runs for a total length of just over 50 km and first opened for business in 1994.

But as impressive as this is, the Channel Tunnel pales in comparison to these giants...

1. The Delaware Aqueduct is the longest tunnel in the world

Location: New York State, United States

Length: ~137,000 m

Type: Water Supply

The Delaware Aqueduct is the world's longest continuous tunnel in the world. It serves as the main water supply tunnel to New York City.

The tunnel was drilled through solid rock and is, on average, around 4 meters wide for most of its course. The aqueduct was built during the Second World War and carries around 1.3 billion US gallons of water a day. 

2. Päijänne Water Tunnel is the second longest tunnel in the world

Location: Southern Finland

Length: ~120,000 m

Type: Water Supply

The Päijänne Water Tunnel is the second longest tunnel in the world at just over 120,000 meters long. It is located in Southern Finland and runs between 30 and 100 meters underground-level.

The tunnel transports fresh water for the millions of inhabitants of Southern Finland's major cities like Helsinki, Espoo, and Vantaa. Construction began in around 1972 and took a total of around 10 years to complete. 

3. The Dahuofang Water Tunnel is the longest in China

Location: Liaoning Province, China

Length: >85,000 m

Type: Water Supply

The Dahuofang Water Tunnel is the third longest continuous tunnel in the world. It is located in the Liaoning Province of China and runs for around 85.3 km. 

The tunnel was built to provide fresh water from the Dahuofang Reservoir to the cities of Shenyang, Fushun, Liaoyang, Anshan, Panjin, Yingkou, and Dalian. Construction began in 2006 and was completed only three years later.

Once the New York City Water Tunnel No. 3 is completed in around 2020, it will replace Dahuofang as the third longest tunnel in the world.

4. Orange–Fish River Tunnel consumed a lot of concrete

Location: South Africa

Length: >82,000 m

Type: Water Supply

The Orange-Fish River Tunnel is an irrigation tunnel located in South Africa. Work began on its construction in 1966 and it was finally completed in 1975.

When completed, the tunnel's length of over 82 km makes it the longest continuous enclosed aqueduct in the southern hemisphere. It took an estimated 842,000 m3 of concrete to line it.

5. The Bolmen Water Tunnel runs for around 82 km

Location: Kronoberg/Scania, Sweden

Length: ~82,000 m

Type: Water Supply

The Bolmen Water Tunnel is another water supply tunnel in Scandinavia. It was built to transport water from Lake Bolmen in Kronoberg to the Swedish province of Skane. 

It supplies water to around 700,000 Swedish citizens and has a cross-section area of around 8 m2. Construction began in 1975 and took around 12 years to complete. 

6. The Túnel Emisor Oriente is the world's longest wastewater tunnel

Location: Mexico City, Mexico

Length: >62,000 m

Type: Water waste

The Emisor Oriente Tunnel is a wastewater treatment tunnel located in Mexico City in Mexico. Its length of 62 km makes it the longest of its kind in the world. 

Construction began in 2008 and was completed in around 2014 using a tunnel boring machine. The tunnel serves around 20 million people as it runs from Mexico City to the Atotonilco Wastewater Treatment Plantin Hidalgo state.

7. Guangzhou Metro Line 3 is the longest metro tunnel in the world

Location: Guangzhou, China

Length: >60,000 m

Type: Metro

The Guangzhou Metro Line 3 is the world's longest metro tunnel in the world. The longest continuous tunnel section of the metro's main branch line runs between Tianhe Coach Terminal and Tiyu Xilu.

Construction of the entire Metro 3 project began in 2001 and was finally completed in 2005. 

8. Gotthard Base Tunnel is the longest railway tunnel in the world

Location: Central Swiss Alps, Switzerland

Length: 2 Sections of ~57,000 m

Type: Railway

Gotthard Base Tunnel is the longest railway tunnel in the world. It is also the longest transit tunnel in the world and has a total underground length of around 151 km. 

Because the total tunnel breaks out at certain points it is not one long continuous tunnel. For this reason, it is at 9th place and not 1st. Construction began in 1999 and the Gotthard tunnel finally opened in 2016.

9. Beijing Subway Line 10

Location: Beijing, China

Length: >57,000 m

Type: Metro

The Beijing Subway Line 10 runs for around 57 km in total and is the second loop line in Beijing's rapid transit system. The whole tunnel runs underground and travels through the Haidian, Chaoyang, and Fengtai districts.

Line 10 is the world's longest subway loop line and one of the longest entirely underground subway lines.