Tunnels are among the greatest achievements in modern engineering. They connect cities, cut travel time, and make it possible to cross mountains, seas, and deserts. From Norway to Japan and China, the world’s longest tunnels showcase human determination to build beyond natural barriers.
In this article, we explore the 10 longest tunnels in the world, focusing on their features, construction challenges, and importance.
Quick Overview: Longest Road Tunnels in the World
| Rank | Tunnel Name | Country | Length (km) | Year Opened | Type |
|---|---|---|---|---|---|
| 1 | Lærdal Tunnel | Norway | 24.51 | 2000 | Road |
| 2 | Yamate Tunnel | Japan | 18.2 | 2015 | Urban Road |
| 3 | Zhongnanshan Tunnel | China | 18.04 | 2007 | Road |
| 4 | Jinpingshan Tunnel | China | 17.54 | 2011 | Service |
| 5 | St. Gotthard Tunnel | Switzerland | 16.84 | 1980 | Road |
| 6 | Tiantaishan Tunnel | China | 15.56 | 2021 | Road |
| 7 | Ryfylke Tunnel | Norway | 14.46 | 2019 | Undersea |
| 8 | Mount Ovit Tunnel | Turkey | 14.34 | 2018 | Road |
| 9 | Arlberg Tunnel | Austria | 13.97 | 1978 | Road |
| 10 | Micangshan Tunnel | China | 13.8 | 2018 | Road |
| 11 | Tokyo Bay Aqua-Line | Japan | 14.0 | 1997 | Undersea |
| 12 | Xishan Tunnel | China | 13.4 | 2020 | Road |
| 13 | Hsuehshan Tunnel | Taiwan | 12.9 | 2006 | Road |
| 14 | Gudvanga Tunnel | Norway | 11.4 | 1991 | Road |
| 15 | Mount Macdonald Tunnel | Canada | 14.6 | 1988 | Rail |
1. Lærdal Tunnel, Norway
The Lærdal Tunnel is the longest road tunnel in the world, stretching over 24.51 kilometers between the towns of Lærdal and Aurland. Completed in 2000, it links eastern and western Norway through steep mountain terrain. Engineers designed it to provide a safer and faster route while maintaining driver comfort with specialized lighting and ventilation systems.
Key Highlights of Lærdal Tunnel:
- Length: 24.51 km
- Location: Between Lærdal and Aurland, Norway
- Opened: 2000
- Type: Road Tunnel
- Unique Feature: Special lighting zones to reduce driver fatigue
- Purpose: Connects major cities and reduces travel time across fjords
2. Yamate Tunnel, Japan
Located in Tokyo, the Yamate Tunnel is the second-longest road tunnel globally, with a length of 18.2 kilometers. Construction took over 20 years due to Tokyo’s dense urban layout. Completed in 2015, it carries heavy traffic through underground expressways, helping reduce congestion on surface roads.
Key Highlights of Yamate Tunnel:
- Length: 18.2 km
- Location: Tokyo, Japan
- Opened: 2015
- Type: Urban expressway tunnel
- Unique Feature: Built under existing city infrastructure
- Purpose: Reduces surface traffic in one of the world’s busiest cities
3. Zhongnanshan Tunnel, China
The Zhongnanshan Tunnel, located in Shaanxi Province, China, spans 18.04 kilometers beneath Zhongnan Mountain. Opened in 2007, it passes through complex geological terrain and reaches a depth of 1,640 meters below the mountain surface. This tunnel connects Xi’an and Ankang, reducing travel time dramatically between northern and southern Shaanxi.
Key Highlights of Zhongnanshan Tunnel:
- Length: 18.04 km
- Location: Shaanxi, China
- Opened: 2007
- Type: Two-bore road tunnel
- Unique Feature: Built deep under a mountain range
- Purpose: Enhances regional connectivity and tourism
4. Jinpingshan Tunnel, China
The Jinpingshan Tunnel in Sichuan, China, is 17.54 kilometers long and serves as an access route to the Jinping Hydropower Station, one of the tallest dams in the world. Completed in 2011, this tunnel was designed for industrial and scientific use and is not open to regular public traffic.
Key Highlights of Jinpingshan Tunnel:
- Length: 17.54 km
- Location: Sichuan, China
- Opened: 2011
- Type: Service/utility tunnel
- Unique Feature: Provides access to Jinping Hydropower Project
- Purpose: Supports power generation and dam operations
5. St. Gotthard Road Tunnel, Switzerland
The St. Gotthard Tunnel in Switzerland stretches 16.84 kilometers, connecting the cantons of Uri and Ticino. Completed in 1980, it was the world’s longest road tunnel for two decades. Built under the Alps, it revolutionized travel between northern and southern Europe by providing a year-round route through the mountains.
Key Highlights Of St. Gotthard Road Tunnel:
- Length: 16.84 km
- Location: Between Göschenen and Airolo, Switzerland
- Opened: 1980
- Type: Road Tunnel
- Unique Feature: First Alpine tunnel of its scale
- Purpose: Enables year-round trade and transport across the Alps
6. Tiantaishan Tunnel, China
The Tiantaishan Tunnel, located in Shaanxi, China, measures 15.56 kilometers and was completed in 2021. It represents the new generation of tunnel engineering in China, built using modern safety systems, advanced lighting, and intelligent monitoring technologies.
Key Highlights of Tiantaishan Tunnel:
- Length: 15.56 km
- Location: Shaanxi, China
- Opened: 2021
- Type: Road Tunnel
- Unique Feature: Equipped with smart safety monitoring systems
- Purpose: Supports faster and safer highway connectivity
7. Ryfylke Tunnel, Norway
The Ryfylke Tunnel is an undersea tunnel connecting Stavanger and Ryfylke in Norway. Opened in 2019, it stretches 14.46 kilometers and descends 292 meters below sea level. It is one of the world’s deepest and longest undersea road tunnels, showcasing Norway’s expertise in sub-sea engineering.
Key Highlights of Ryfylke Tunnel:
- Length: 14.46 km
- Location: Stavanger–Ryfylke, Norway
- Opened: 2019
- Type: Undersea road tunnel
- Unique Feature: Deepest underwater road tunnel globally
- Purpose: Connects island communities and boosts regional trade
8. Mount Ovit Tunnel, Turkey
The Mount Ovit Tunnel in Turkey measures 14.34 kilometers and connects the towns of İkizdere and İspir. Completed in 2018, it passes through the Pontic Mountains and provides year-round access to areas previously blocked by snow in winter.
Key Highlights of Mount Ovit Tunnel:
- Length: 14.34 km
- Location: İkizdere–İspir, Turkey
- Opened: 2018
- Type: Mountain road tunnel
- Unique Feature: Enables year-round connectivity through snowy terrain
- Purpose: Facilitates transport and trade across northeastern Turkey
9. Arlberg Tunnel, Austria
The Arlberg Tunnel, located in western Austria, stretches 13.97 kilometers between the provinces of Tyrol and Vorarlberg. Completed in 1978, it was one of Europe’s earliest long-distance tunnels, offering a safer alternative to crossing the high Alpine passes.
Key Highlights of Arlberg Tunnel:
- Length: 13.97 km
- Location: Tyrol–Vorarlberg, Austria
- Opened: 1978
- Type: Road Tunnel
- Unique Feature: Historic Alpine crossing route
- Purpose: Improves transport and tourism across Austria’s western region
10. Micangshan Tunnel, China
The Micangshan Tunnel in Sichuan, China, measures 13.8 kilometers and was opened in 2018. It is one of the latest additions to China’s expanding highway network, built to enhance accessibility across mountainous areas. With advanced ventilation and lighting systems, it ensures safe and efficient driving conditions.
Key Highlights of Micangshan Tunnel:
- Length: 13.8 km
- Location: Sichuan, China
- Opened: 2018
- Type: Road Tunnel
- Unique Feature: Modern tunnel design with strong safety measures
- Purpose: Promotes connectivity and economic growth in mountainous regions
Engineering Significance of the World’s Longest Tunnels
The construction of these tunnels represents a blend of innovation, precision, and perseverance. Modern tunnels must withstand geological pressure, temperature variation, and water infiltration. Engineers use technologies like tunnel-boring machines (TBMs), smart ventilation systems, and seismic-resistant linings to ensure durability and safety.
Countries like China, Norway, and Japan have led tunnel-building due to their mountainous or coastal terrains, demanding advanced infrastructure for connectivity.
Challenges in Building Long Tunnels
Building tunnels longer than 10 km poses major challenges:
- Geological Complexity: Builders must analyze rock stability and groundwater movement.
- High Costs: Projects often run into billions of dollars due to advanced equipment and safety systems.
- Ventilation & Safety: Long tunnels need constant airflow and emergency exits.
- Environmental Impact: Construction can disturb ecosystems and require extensive mitigation planning.
Despite these challenges, the results are lasting symbols of engineering mastery that connect regions and nations.
FAQs About the Longest Tunnels in the World
1. Which is the longest road tunnel in the world?
The Lærdal Tunnel in Norway is the longest road tunnel in the world, measuring 24.51 kilometers in length.
2. Which tunnel holds the record for overall length globally?
The Delaware Aqueduct in the USA is the world’s longest tunnel overall, stretching about 137 kilometers.
3. Which is the longest underwater road tunnel?
The Ryfylke Tunnel in Norway is the world’s longest and deepest underwater road tunnel.
4. How long did it take to build the Yamate Tunnel in Japan?
Construction of the Yamate Tunnel began in 1992 and was completed in 2015, taking nearly 23 years.
5. What is unique about the Zhongnanshan Tunnel in China?
It runs 1,640 meters below Zhongnan Mountain, making it one of the deepest mountain tunnels ever built.
6. Which country has built the most long tunnels?
China leads the world in tunnel construction, with several of the top 10 longest tunnels located within its borders.
7. Why was the St. Gotthard Tunnel built in Switzerland?
It was constructed to provide year-round access through the Alps and improve transport between northern and southern Europe.
8. What makes the Mount Ovit Tunnel important for Turkey?
It provides a year-round route through snow-covered mountains, supporting trade and tourism.
9. Which is the newest long tunnel on the list?
The Tiantaishan Tunnel in China, opened in 2021, is the newest among the world’s longest tunnels.
10. Why are tunnels crucial for global transport?
Tunnels reduce travel time, connect remote regions, and enable trade and mobility across natural barriers.