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Dali-Ruili railway tunnel faces 19 seismic faults and 102-degree heat at 1,155 meters deep
While the Ferrogrão railway project has been stalled for 16 years in Brazil, Chinese engineers are drilling 34.5 km of rock under the Gaoligong mountain in Yunnan. The tunnel will be Asia’s longest railway tunnel.
The project is in its final phase, according to a report by The Star published on February 19, 2026. The main bore is expected to be completed in December 2027.
Commercial operation of the entire railway begins in 2028. This marks 14 continuous years of construction since its launch in 2011.
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According to official data from the China Railway Tunnel Group, the CREC subsidiary responsible for the work, progress reached 50% in February 2026.
Therefore, the final half of the tunnel still needs to be drilled under the same extreme geological conditions. Chinese engineers say the remaining work is as difficult as the first half.
Thus, the Gaoligong tunnel enters the pantheon of the greatest achievements in global railway engineering. It is already on the list of the 7 largest tunnels on the planet in any mode.
Why the Gaoligong tunnel is considered the most difficult railway tunnel in the world
The Gaoligong crosses 19 active seismic faults. This number is higher than any other railway project on the planet.
For comparison, the Tianshan tunnel, also in China, encountered 16 fault zones. The Gotthard Base, in Switzerland, crosses only 4 relevant faults.
According to details from Tunnels and Tunnelling, the project also faces extreme underground heat. Some sections have temperatures up to 102 degrees Celsius.
The maximum depth of the tunnel reaches 1,155 meters. It is one of the highest points of rock cover ever encountered in a railway under construction.
According to an analysis of the Dali-Ruili railway technical record, the underground hydrological system of the Hengduan region operates under high pressure.
For this reason, excavations in certain sections have already triggered small collapses. Chinese engineers describe episodes where they advanced 3 meters and lost 1 to 2 meters in collapses.
In fact, Chinese engineering created a term for the problem: “three highs, four actives.” It means high altitude, high geothermal heat, high water pressure, active geological and seismic faults.
What is the Dali-Ruili railway and where is Gaoligong located
The Gaoligong is part of the Dali-Ruili railway, which connects Dali (central Yunnan) to Ruili (a Chinese city on the border with Myanmar). It spans 336.39 km in total.
The first phase of the railway, between Dali and Baoshan (133 km), was inaugurated on July 22, 2022. It took 14 years to complete.
As reported by the South China Morning Post, the second phase began in 2015. It includes the Gaoligong tunnel as a central obstacle.
Thus, 75% of the entire Dali-Ruili route is made up of bridges and tunnels. This is an unprecedented percentage for recent Chinese railways.
For this reason, the entire railway became known as “the most difficult in the world to build.” In Chinese, it is nicknamed 关键控制工程 (critical control project).
The Gaoligong in particular was classified as a “throat project” (咽喉工程). Without it, nothing in the second section can operate.
When operational, the Dali-Ruili railway will reduce the journey between Kunming (Yunnan’s capital) and Ruili from 9 hours to 5 hours.
How Chinese engineering is solving the obstacles
The China Railway Tunnel Group uses a multi-front simultaneous strategy. Different sections of the Gaoligong are tackled at the same time.
There is a 3.8 km inclined shaft that serves as a secondary access. It is the largest inclined shaft ever used in a railway project in China.
According to reports from the Chinese Engineering Magazine, the system allows for reverse drainage of groundwater. Without it, the tunnel would be flooded every kilometer.
In parallel, TBM machines use a pressurized air system to prevent collapses during drilling in high hydrostatic pressure zones.
For this reason, the project required the development of unprecedented cement injection techniques. The method now serves as a reference for other similar projects around the world.
According to official data published by the China News Service, the project completed the underground concrete mixing stations in December 2024.
In fact, concrete produced within the tunnel reduces logistical costs. The stations are located kilometers from the main portal.
- Length: 34.5 km (Asia’s longest railway tunnel)
- Maximum depth: 1,155 meters
- Internal temperature: up to 102 degrees Celsius
- Seismic faults crossed: 19 active
- Current progress (Feb 2026): 50% after 9 years
- Breakthrough predicted: December 2027
- Commercial operation: 2028
Comparison with Ferrogrão and the paralysis of Brazilian infrastructure
While the Gaoligong advances 50% in 9 years under 102 degrees of heat, Brazil’s Ferrogrão has been stalled for 16 years. The BR-163 railway project accumulates legal and environmental impasses.
According to analysis by BNAmericas, Ferrogrão involves an investment of US$16 billion for 933 km of tracks in Brazil.
Thus, the Brazil-China comparison is not just technical. It shows a decision-making abyss between governments regarding strategic projects.
For more context on this direct comparison, it is worth reading Click Petróleo e Gás’s coverage of other strategic mega-projects.
Another parallel with Chinese mega-engineering also appears in other Brazilian investigations by Click Petróleo e Gás.
According to details from Bastille Post, integration with Myanmar was reduced. The project’s original extension to Mandalay halted due to political conflict in Myanmar.
What Gaoligong means for global energy supply chains
The Gaoligong tunnel is part of China’s Belt and Road Initiative (BRI). The axis serves to transport oil and gas from Myanmar to Yunnan.
Therefore, the Chinese energy corridor gains logistical redundancy. Railway, oil pipeline, and gas pipeline follow parallel routes through the same region.
According to data from the China-Myanmar economic corridor, the axis currently moves about 12 billion cubic meters of natural gas per year.
Thus, when the tunnel becomes operational in 2028, the railway will increase the capacity for general cargo movement. This includes fuels, equipment, and food.
In fact, the economic impact for Yunnan is estimated at over 1 trillion yuan in 30 years. This data comes from the provincial government’s strategic plan.
It is worth noting that the schedule may still be delayed further. The 1,155 meters of depth and the 19 remaining seismic faults could bring surprises.
Despite this, the 50% progress in February 2026 is already considered a milestone. The Gaoligong will redefine the standard of global railway engineering.
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