The longest road tunnels in the world

Muzhailing Tunnel, China – 9.46 miles (15.22km)

A great many challenges faced the designers and builders of the Muzhailing Tunnel in China’s Gansu Province. For starters, it’s built at high altitude and also in an area of active seismic activity, which means it’s prone to earthquakes.

Although not ideal conditions for creating one of the world’s longest road tunnels, the build used a technology called NPR anchor cabling. This secures the structure into the surrounding rock and allows the tunnel to withstand deformation as the ground moves.

Muzhailing Tunnel, China – 9.46 miles (15.22km)

In common with most modern road tunnels, the Muzhailing Tunnel consists of two separate tubes, each carrying the stream of traffic in the opposite direction to the other. Construction work on this tunnel started in 2016 and reached its finish in 2024, with further complications to the build caused by the thin air at its high altitude and its effect on the workers.

Now complete, the Muzhailing Tunnel is widely studied by tunnelling experts for the way it deals with such difficult terrain.

Tiantaishan Tunnel, China – 9.67 miles (15.56)

It cost 2.75 billion Chinese Yuan (£300 million) to complete the Tiantaishan Tunnel, which is something of a bargain in the world of road tunnels. Started in 2016, the Tiantaishan Tunnel was finished and working by 2021, which is again something of a record when it comes to build time.

All of this is even more impressive when you consider the high altitude of the tunnel and the bitterly cold weather in Shaanxi Province in northwest China.

Tiantaishan Tunnel, China – 9.67 miles (15.56)

When construction started in November 2016, there were 2000 workers spending their shifts underground in the Qinling Mountains. They also lived there for the duration of the build work. As part of the construction of the Tiantaishan Tunnel, a new smart lighting system was developed that delivers a more natural light inside its depths.

This set-up also provides different light patterns and designs on the tunnel’s walls to ward off boredom as drivers traverse its 9.67-mile length in either of the three-lane tunnel tubes.

Gotthard Road Tunnel, Switzerland – 10.46 miles (16.84km)

Previously the longest road tunnel in the world, the Gotthard Base Tunnel in Switzerland has slipped down the ranking as new projects have overtaken for length. However, the Gotthard has been in operation for much longer than any other in the top 10 as it opened in 1980.

Work started on the Gotthard Road Tunnel in 1970 and it carries traffic to a maximum height if 1175-metres (3855-feet), which is higher than Yr Wyddfa (Mount Snowdon) in Wales.

Gotthard Road Tunnel, Switzerland – 10.46 miles (16.84km)

It takes around 13 minutes to drive through the Gotthard Road Tunnel as the 80kmh speed limit is strictly enforced. There is also a toll charge to pay for using the tunnel and it’s capable of carrying up to 24,000 vehicles per day. The Gotthard Base Tunnel is unusual in modern road tunnelling for using a single tube to carry both directions of traffic.

In 2016, 57% of the Swiss population voted in favour of building a second Gotthard road tunnel in a referendum.

Jinpingshan Tunnel, China – 10.90 miles (17.54km)

While all of the other road tunnels in the top 10 are open to the public, the Jinpingshan Tunnel restricts what traffic can use it. This is because the tunnel was built to provide access to the Jinping Dam, which is the world’s highest dam, and access between this and another hydropower dam. The Jinpingshan Tunnel runs through an area noted for its geological activity in south-west China.

This is partly why access to the tunnel is limited, and also because of security surrounding the hydroelectric complex at the dam.

Jinpingshan Tunnel, China – 10.90 miles (17.54km)

At its deepest point, the Jinpingshan Tunnel runs 2375-metres beneath the earth’s surface, and more than half of the tunnel’s entire length sits at more than 1500-metres deep. It took five years to build the Jinpingshan Tunnel and, at the time, was the longest tunnel made with a blind heading.

This is where each end of the tunnel is started simultaneously and meet in the middle. Total cost of Jinpingshan Tunnel came to 1.3 billion Chinese Yuan (£146 million).

Zhongnanshan Tunnel, China – 11.21 miles (18.04km)

The Zhongnanshan Tunnel is not far from the Tiantaishan Tunnel but outdoes its near neighbour in overall length and how deep it travels under the Earth’s surface. With a maximum depth of 1640-metres, the Zhongnanshan Tunnel is among the deepest in the world. Despite this, it still took only five years to complete the tunnel, which is about the same time as many shorter tunnels that travel at shallower depths in China.

Work started in 2002 on the Zhongnanshan Tunnel, and it was the longest tunnel in Asia when it opened to traffic in 2007.

Zhongnanshan Tunnel, China – 11.21 miles (18.04km)

It cost around 3.2 billion Chinese Yuan (£350 million) to complete the Zhongnanshan Tunnel. This makes it one of the most expensive road tunnels to date in China. Three ventilation shafts provide fresh air to each of the two tunnels, and each tube carries traffic in the opposite direction to the other, so the streams are never together.

Along its 11.21-mile length, there are different coloured lights and patterns projected onto the tunnel’s roof, and artificial plants to provide stimulation for drivers and prevent fatigue.

Yamate Tunnel, Japan – 11.3 miles (18.20km)

The Yamate Tunnel in Tokyo, Japan is like London’s Blackwall Tunnel but on a grand scale. Where the Blackwall Tunnel is a mere three quarters of a mile long and is as close as 1.7-metres from the riverbed, the Yamate Tunnel runs to 11.3 miles and passes as much as 30-metres beneath the Japanese capital city’s population.

The Yamate Tunnel still holds the honour of being the longest urban tunnel in the world.

Yamate Tunnel, Japan – 11.3 miles (18.20km)

It took 15 years for the Yamate Tunnel to be completed, with delays due to objections from residents and environmental concerns. However, the tunnel was given the go-ahead as it would ease traffic on Yamate Street that runs above the tunnel. Both of the 11-metre diameter tubes that form the Yamate Tunnel have emergency telephones positioned every 100-metres along their length.

There is also a sophisticated filtration system to remove particulate emissions from the air extracted from the tunnels.

WestConnex, Australia – 13.67 miles (22.0km)

The WestConnex Tunnel was finished in November 2023 and is part of a plan to ease congestion in the city of Sydney. To date, the tunnel is the largest road infrastructure project ever undertaken in Australia and the 13.67-mile tunnel is part of a longer overall 20.5-mile stretch of traffic-reducing motorway.

This will eventually link Sydney’s suburbs, airport, north shore, and city centre. The land above the WestConnex Tunnel has mostly been given over to parks, playgrounds, and open space for the city’s inhabitants to relax.

WestConnex, Australia – 13.67 miles (22.0km)

The WestConnex Tunnel is the longest underground stretch of public road in Australia, and it’s thought to have cost A$10 billion (£5.1 billion). This figure set a new record for transport spending by the New South Wales Government, and it’s estimated the fully completed project will come in at A$45 billion (£23.1 billion).

However, the government also states the tunnel contributes to A$22 billion (£11.3 billion) in savings due to reduced travel time and journey reliability.

Lærdal Tunnel, Norway – 15.23 miles (24.51km)

Topping the longest road tunnels in the world is the Lærdal Tunnel in Norway. This 15.23-mile underground construction was started in 1995 and opened to the public in 2000. It took some 20 years to agree to the construction of the tunnel, which cost 1.1 billion Norwegian Kroner (£85 million) to complete, which represents great value in the world of roads tunnelling.