Cars driving through a road tunnel

We have all probably travelled through tunnels, whether by car or train, but it is usually just for a fleeting few moments. Imagine spending 20 minutes travelling through the same tunnel, as drivers and passengers do in the longest road and railway tunnels in the world! These tunnels are extraordinary feats of modern engineering, plotting a course beneath mountains and seas, incorporating innovative tunnelling and ventilation technology, and sometimes taking decades to complete.  

Here is the Go Construct guide to the world’s longest road tunnels and rail tunnels.  


The longest road tunnels in the world

Lærdal, Norway 

The road tunnel between Lærdal and Aurland in Norway is the longest road tunnel in the world, at 24.5 km (15.2 miles). The tunnel was built between 1995 and 2000, and enables road travel between Oslo and Bergen through the mountainous Filefjell region.  

It is a two-lane tunnel which in its design takes into account the significant mental challenge drivers face travelling for so long (it takes about 20 minutes) through a tunnel. The tunnel walls are lit in blue with yellow light at a lower level to give the effect of sunrise, and there are three areas where the tunnel opens out with space on either side of the lanes, called ‘caves’, so that motorists can take a break if they need to. There are signs that tell drivers how far they have driven in the tunnel, and how far they have to go, as well as rumble strips in the centre of each lane.  

WestConnex, Sydney 

The extensions to the M4 and M8 motorways in Sydney, Australia were opened in 2023 and create a tunnel that is 22 km long. It is known as the WestConnex tunnel and reduces travel time by 40 minutes between the suburb of Parramatta and Sydney Airport. It has caused controversy because of the high project cost and the fact that it has been built in residential areas. Over 200 homes were compulsorily purchased and demolished to make way for the construction.  

WestConnex was constructed to help alleviate the traffic problems of central Sydney, which is considered to have greater congestion problems than New York City, and to create jobs and better access to the city for people living in the western suburbs.   

Yamate Tunnel, Tokyo 

The Yamate Tunnel is an 18.2km (11.3 miles) road tunnel in Tokyo that forms part of the Central Circular Route of the Shuto Expressway. It was opened in stages, with the first section taking 15 years to build and opening in 2007, while the last section was not completed until 2015. Work had first begun in 1992, making it one of Japan’s longest-running modern engineering projects.   

Zhongnanshan Tunnel, Shaanxi, China 

Built under the Zhongnan Mountains in Shaanxi Province, the Zhongnanshan Tunnel is the longest two-tube road tunnel in China. It is 18km (11.2 miles) long, with elevations that range from 896m to 1026m. The tunnel cost US$410 million and was built between March 2002 and December 2007.  

It is part of a national highway network and uses an innovative lighting system. Parts of the tunnel are exceptionally well-lit and incorporate features such as artificial trees to reduce driver fatigue and make driving through the tunnel a safer and more pleasurable experience.


The longest rail tunnels in the world

Gotthard Base Tunnel, Swiss Alps 

At 57km (35.5 miles) long, the Gotthard Base Tunnel is the longest rail tunnel in the world. It is also the deepest, and the first flat, low-level route through the Swiss Alps. Construction began in 1999 and the tunnel opened in 2016. It can carry high-speed passenger trains and freight and significantly cuts the journey time for people travelling between Northern and Southern Europe.  

The Gotthard Base Tunnel has a maximum gradient of 2.6%, making it much easier and quicker for trains to travel through the Swiss Alps. 28 million tonnes of rock were extracted during the monumental construction project. A new cement formula was developed specifically for the project, with a setting time of 11 hours instead of 6. This enabled concrete workers to transport the cement much longer distances to where it was needed without requiring a concrete plant to be built just for the tunnel’s construction.  

Seikan Tunnel, Tsugaru Strait, Japan 

One of the oldest tunnels on our list, the Seikan rail tunnel was opened in 1988. It links the Japanese islands of Hokkaido and Honshu and is 53.8km (33.4 miles) long. It runs under the Tsugaru Strait, with the track laid approximately 100m below the seabed.  

Work began in 1971, and it was one of the most ambitious engineering projects in Japan’s history. By the time it opened, however, travel trends had changed, and it was much quicker to fly between Tokyo and Sapporo than to take the Shinkansen (bullet train) service, which used the Seikan tunnel. There are fewer passengers using the route than first predicted, although freight trains still regularly use the tunnel.  

A train leaving a tunnel 
Eurostar train exiting the Channel Tunnel

Channel Tunnel, UK/France 

The Channel Tunnel is 50.4km (31.4 miles) long, and has the longest stretch of undersea tunnelling in the world. LeShuttle and Eurostar trains run between the UK and France for a total of 37.9 km (23.5 miles) underneath the Channel. There had been talk of a tunnel between the two countries since the early 19th century, but it wasn’t until 1987 that digging finally started on the joint venture between the UK and French governments. 

The tunnelling was done by giant tunnel-boring machines on either side of the Channel. 13,000 engineers, technicians and skilled construction workers were employed on the project, and the tunnel was opened in 1994.  

Yulhyeon Tunnel, Gyeonggi, South Korea 

The 50.3km Yulhyeon Tunnel runs between the southeastern part of Seoul and Gyeonggi province in South Korea. It forms the bulk of the 61km Suseo High-Speed Railway, where trains can travel at speeds of up to 300 km/h (186 mph).  

The Yulhyeon Tunnel was built over a fault line called the Singal Fault, an area known for seismic activity. This has called into question the structural stability of the tunnel, and surveys have shown the track structure to be uneven in some places, forcing trains to travel at lower speeds and ground reinforcement measures to be made. 


Discover tunnelling careers

If you would like to work on major tunnelling projects like these, there are plenty of opportunities available. Find out more about working in tunnelling at Go Construct:  

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