Recently, 9 Chinese projects were successfully selected as among the "50 Tunnel Projects with Global Influence in the Past 50 Years," drawing widespread attention.

Tunnels that bore through mountains and cross rivers and seas help form a 159,000-kilometer railway network, a 45,000-kilometer high-speed rail network, a 5.441-million-kilometer highway network, and an 184,000-kilometer expressway network, connecting a mobile China, bearing witness to economic development, and demonstrating scientific and technological strength.

The world's longest spiral highway tunnel, the world's highest-altitude high-speed rail tunnel, the world's largest-diameter single-tube double-deck tunnel... Today's China has built more than 50,000 kilometers of railway and highway tunnels, opening up "choke points" and forming the world's largest high-speed railway network and expressway network.

Recently, at the 2024 World Tunnel Congress held in Shenzhen, the International Tunnelling and Underground Space Association (hereinafter referred to as the "ITA") released the "50 Tunnel Projects with Global Influence in the Past 50 Years." Nine Chinese projects were successfully selected, the largest number and the highest proportion.

Qinling Tunnel of the Xi'an–Ankang Railway

New Guanjiao Tunnel of the Qinghai–Tibet Railway

The integrated immersed tube transport and installation vessel transporting the immersed tube tunnel elements and the final joint of the Shenzhen–Zhongshan Link at sea

Multiple tunnel projects break world records; from old to new, witnessing the evolution of China's tunnel technology

The Shamalada Tunnel of the Chengdu–Kunming Railway, the Dayaoshan Tunnel of the Hengyang–Guangzhou double-track line of the Beijing–Guangzhou Railway, the Qinling Tunnel of the Xi'an–Ankang Railway, the New Guanjiao Tunnel of the Qinghai–Tibet Railway, the immersed tube tunnel of the Hong Kong–Zhuhai–Macao Bridge, Shenzhen Metro Line 14, the subsea tunnel of the Shenzhen–Zhongshan Link, and the Second Jiaozhou Bay Subsea Highway Tunnel in Qingdao... Opening the catalog of the "50 Tunnel Projects with Global Influence in the Past 50 Years," the selected Chinese projects bear witness to the evolution of China's tunnel technology over the past decades.

The Shamalada Tunnel, a controlling project of the Chengdu–Kunming Railway, is located in an area at an altitude of more than 2,200 meters and was regarded by foreign geologists as a "forbidden zone," with underground rivers, faults, and mudslides everywhere.

In March 1959, construction of the Shamalada Tunnel began. Using sledgehammers and steel chisels to drill holes and blast bit by bit, workers could often advance only half a meter a day. Under such arduous conditions, the Shamalada Tunnel was successfully holed through in November 1966, helping the Chengdu–Kunming Railway open to traffic successfully.

"'For there is sacrifice, there is great aspiration; we dare to teach the sun and moon to change places in the new sky.' The Shamalada Tunnel laid the foundation for the spirit of Chinese tunnel builders: fearing neither hardship nor fatigue, and daring to be pioneers," said Yan Jinxiu, former president of the ITA and chief expert of the China Railway Academy Co., Ltd.

The Dayaoshan Tunnel, a key tunnel of the Hengyang–Guangzhou double-track line of the Beijing–Guangzhou Railway, has a total length of 14.295 kilometers and is China's first ultra-long double-track electrified railway tunnel to open to traffic.

"The Dayaoshan Tunnel had to pass through dozens of large and small faults, with fractured rock strata, extremely poor stability, and strong permeability. The disturbance to the mountain caused by tunnel construction could easily lead to collapse and mud and water inrush," recalled a relevant person in charge of the China Railway Tunnel Group. To build the Dayaoshan Tunnel, the old methods would not work; innovation had to be pursued.

To this end, the China Railway Tunnel Group actively carried out technological innovation, introduced advanced technology and equipment, and adopted the entirely new construction technique known as the "New Austrian Tunnelling Method" to build the Dayaoshan Tunnel, setting 11 records. In 1992, the Dayaoshan Tunnel won the Special Prize of the National Science and Technology Progress Award, leading China's tunnel construction to achieve a leapfrog breakthrough across the entire system.

Since then, China's tunnel technology has grown rapidly.

The Qinling Tunnel, a controlling project of the Xi'an–Ankang Railway, is China's first railway tunnel constructed using a full-face tunnel boring machine (TBM), marking that China's tunnel construction had entered the stage of factory-style shield/TBM construction.

The New Guanjiao Tunnel, a controlling project of the Xining–Golmud second line of the Qinghai–Tibet Railway, is the first tunnel in the history of tunnel construction to be built with a length of more than 30 kilometers at an altitude above 3,000 meters and under the complex geological conditions of the Qinghai–Tibet Plateau.

The immersed tube tunnel of the Hong Kong–Zhuhai–Macao Bridge is the world's longest highway immersed tube tunnel and the only deeply buried immersed tube tunnel, as well as China's first offshore immersed tube tunnel. The subsea portion of the tunnel is about 5,664 meters long, composed of 33 giant immersed tube elements and one final joint for the closure section, with a maximum installation water depth of more than 40 meters. It is called the Everest of transportation engineering.

The subsea tunnel of the Shenzhen–Zhongshan Link has a total length of about 6.8 kilometers, of which the immersed tube tunnel is about 5 kilometers long. It is the world's longest and widest steel-shell concrete immersed tube tunnel.

"In 1990, when China first hosted the World Tunnel Congress, we received help from countries around the world," Yan Jinxiu said proudly. Thirty-four years later, through extensive engineering practice, we have accumulated a batch of innovative achievements and experience that we can share with peers around the world.

The scale of tunnel construction has grown rapidly, forming the world's largest high-speed railway network and expressway network

From 1990 to the present, over 34 years, the scale of China's tunnel construction has grown 24-fold, with a construction mileage exceeding half of the world's total.

Today, China has built more than 50,000 kilometers of railway and highway tunnels, opening up "choke points" and forming the world's largest high-speed railway network and expressway network.

Data show that by the end of 2023, there were 18,573 railway tunnels in operation, with a total length of 23,508 kilometers. Among them, there were 4,561 high-speed railway tunnels, with a total length of 7,735 kilometers. By the end of 2022, there were 24,850 highway tunnels in operation, with a total length of 26.7843 million linear meters.

The road network extends, and trains speed along. In the first quarter of this year, railways nationwide carried 1.014 billion passenger trips, with an average of 11.147 million passenger trips per day, up 28.5% year on year. During the May Day holiday, cross-regional passenger flows across society reached 1.358 billion trips, demonstrating the surging momentum of China's economy.

Today's China has built 8,543 kilometers of subway, significantly improving urban operational efficiency and greatly facilitating public travel.

Take Shenzhen as an example. With a land area of less than 2,000 square kilometers and an actual managed and served population of more than 21 million, it has continuously expanded development space underground to make life more convenient for residents.

By the end of 2023, the operating mileage of Shenzhen's urban rail transit network (including trams) had increased to 567.1 kilometers, and the number of stations had increased to 393 (including transfer stations, excluding Fulin Station). The density of the urban rail transit network (calculated by administrative district area) reached 0.28 kilometers per square kilometer. In 2023, Shenzhen's rail transit network (including trams) carried a total of about 2.711 billion passenger trips, with passenger volume increasing by more than 56% year on year.

Today's China has built 5,100 kilometers of underground utility tunnels, effectively promoting intensive urban development and enhancing urban resilience.

Xiong'an New Area is the first city in China to adopt fully underground utility tunnels. In Rongdong District, the first concentrated built-up area of the new area, no manhole covers are seen on the streets and no power lines overhead; all pipelines for electricity, gas, water supply, and communications have been placed in underground utility tunnels.

Relying on new-generation information technologies such as big data and the Internet of Things, the utility tunnels build a wireless IoT sensing network and a smart operation and maintenance platform, conducting online and offline inspections and patrols in pursuit of safe, smart, precise, and efficient operation. Not only Xiong'an New Area but also Beijing, Chongqing, Zhuzhou, and other cities have built underground utility tunnels, effectively saving land space and releasing development space.

"China has become the country with the largest number of tunnels, the largest construction scale, and the fastest development speed in the world today," said Ni Hong, Minister of Housing and Urban-Rural Development. Tunnel and underground engineering construction has enabled full use of land and smooth flow of goods, promoted rapid economic and social development, effectively improved people's livelihoods, and played an important role in Chinese-style modernization.

Moving toward full automation and intelligence; China's tunnel construction has entered a stage of complete independent innovation

"Today, we can proudly say that China's tunnel construction concepts and construction methods have reached the world's leading level," Yan Jinxiu said. In particular, tunnel construction equipment represented by large shield machines has been fully localized, and with extreme technical challenges represented by river- and sea-crossing and high-altitude deeply buried tunnels, China's tunnel construction has entered a stage of complete independent innovation and is advancing toward a higher stage of full automation and intelligence.

On the morning of April 29, as the cutterhead of the "Linghang" shield machine slowly rotated, it marked that the Chongtai Yangtze River Tunnel had fully entered the shield construction stage, beginning a journey of ultra-large-diameter shield single-head boring across the Yangtze River.

It is reported that the "Linghang" shield machine will operate 89 meters underwater in the Yangtze River, boring 11.3255 kilometers in a single heading, connecting Chongming in Shanghai and Taicang in Jiangsu, and realizing for the first time high-speed rail crossing the river without slowing down.

Not only the Chongtai Yangtze River Tunnel, but many large-section tunnels are currently under construction in China, such as the Suzhou East Tunnel on the newly built Nantong–Ningbo high-speed railway, known as "China's first urban high-speed rail tunnel," and the Jintang Subsea Tunnel of the Ningbo–Zhoushan Railway, the world's longest subsea high-speed rail tunnel.

Tackling tunnel projects under more complex geological conditions is one of the characteristics of China's tunnel construction. The Gaoligongshan Tunnel is one representative.

As a controlling project of the entire Dali–Ruili Railway, the Gaoligongshan Tunnel is the world's first extra-long railway tunnel crossing the Hengduan Mountains. The tunnel has a maximum burial depth of 1,155 meters and passes through as many as 18 types of strata, including 19 fault zones. It is called a "geological museum" in the history of railway construction, encompassing almost all adverse geological conditions and major risks in tunnel construction.

As of May 5, the main tunnel of the Gaoligongshan Tunnel had been completed for 17.8 kilometers, with 16.7 kilometers remaining; the parallel pilot tunnel had been completed for 18.1 kilometers, with 16.4 kilometers remaining.

This tunnel is constructed by the China Railway Tunnel Group. "Of the 8 projects from the Chinese mainland shortlisted this time, the China Railway Tunnel Group participated in the construction of 7. The Gaoligongshan Tunnel is our new milestone," said a relevant person in charge of the China Railway Tunnel Group.

Recently, more than 30 international tunnel experts attending the World Tunnel Congress made a special trip to visit the shield tunnel section of the Shenzhen Qianhai–Huanggang section of the Guangzhou–Shenzhen–Dongguan intercity railway. "Within just 3.5 kilometers, this tunnel has to pass beneath 28 major risk points such as high-speed rail and metro lines, and also beneath 128 pipelines. It is the shield tunnel project with the highest comprehensive risk and the greatest construction difficulty among similar projects at home and abroad," said Liu Ziming, project manager of the China Railway 22nd Bureau Group.

"At present, global tunnel and underground engineering is still in a period of rapid development, with broad development space," said Chen Yun, Party Secretary and Chairman of China Railway Engineering Group Co., Ltd. Looking to the future, Chinese tunnel builders will not only build ultra-deep, ultra-long, and ultra-complex tunnel projects and underground spaces with larger cross-sections and greater burial depths, but will also be committed to practicing the concept of green and low-carbon development, actively developing intelligent construction and smart operation and maintenance, and building world-class tunnel projects.