Snow Mountain Tunnel: From an "Impossible Mission" to a Bloody and Tearful Miracle of Taiwan's Engineering

On December 15, 1997, a water inrush accident nearly claimed 300 lives, turning a TBM worth NT$1 billion into scrap metal. This tunnel, listed by the *Encyclopedia Britannica* as one of the world's most arduous engineering projects, is not just a traffic artery but a miracle forged in blood and tears by 25 martyrs and countless unsung heroes chiseling through tetrahedral sandstone harder than steel.

30-Second Overview:
The Snow Mountain Tunnel is approximately 12.9 kilometers long, making it Taiwan's longest highway tunnel and one of the world's largest dual-bore highway tunnel complexes, comprising 58 tunnels of varying sizes 1. Construction began in 1991 and took 15 years and approximately NT$18.5 billion to complete. This excavation history was filled with fault water inrushes and collapse disasters, leading international experts to declare it an "impossible mission." It was finally opened to traffic in 2006 by the Taiwan engineering team relying on willpower and innovative construction methods, reducing the travel time from Taipei to Yilan from 2 hours to approximately 40 minutes.

December 15, 1997: The Moment That Almost Stopped Breath

At 8:00 AM on December 15, 1997, deep within the westbound lane of the Snow Mountain Tunnel, the earth emitted a dull, compressive sound. The full-face Tunnel Boring Machine (TBM), costing NT$1 billion, was trapped in the broken zone of the Jinying Fault, with water continuously seeping from above 2.

"Water continued to surge in from all directions, and the cracks in the tunnel segments became increasingly severe; there were two or three hundred people on site fighting to save the situation," recalled Lian Yao-dong (Lien Yao-tung), then Deputy Director of Electromechanical Systems, his tone still carrying a trace of lingering fear 2. At that time, high-pressure water carrying mud and sand put the tunnel structure at risk of collapse. By noon, Lian Yao-dong sensed something was wrong and ordered everyone to evacuate.

In the chaos of the evacuation, he suddenly realized that the TBM's 22.8 KVA high-voltage power supply had not been turned off. If the water came into contact with the electricity, all 300+ people on site would be killed. He risked his life to rush back to the control room to shut off the power. Just as he turned and ran for his life, a earth-shattering collapse sound echoed from behind. This "excavation artifact," once full of hope, was thus buried in the surge of ancient groundwater, becoming one of the most tragic costs in the history of the Snow Tunnel 2.

This disaster rendered the TBM obsolete, forcing the engineering team to face immense pressure and switch to traditional NATM (New Austrian Tunneling Method), while opening additional working faces (such as No. 2 Shaft) to turn the progress around 3. This moment presented the core tension of the Snow Mountain Tunnel's 15-year construction history: geology, technology, willpower, and luck pulling the engineering progress in all directions simultaneously.

Pushing the Limits of Geology: Tetrahedral Sandstone Harder Than Steel and Millennia-Old Water Inrushes

Why was the Snow Mountain Tunnel so difficult to build? The answer lies in the unique and harsh geological structure of the Xueshan Mountain Range.

The Snow Tunnel had to pass through 6 major faults, 98 shear zones, and 36 water inrush zones 4. The most dreaded by engineering personnel was the "tetrahedral sandstone," known as the "steel of the rock world." This geological formation has a strength of 1200–2785 kg/cm², a quartz content of 82%, and a Mohs hardness between 6 and 7, far exceeding the 5.5 of general steel rebar 5. The 3,671-meter-long tetrahedral sandstone section caused the TBM, originally expected to advance quickly, to move extremely slowly here, averaging only slightly more than 1 meter per day, and it was once stuck and stalled for up to 885 days 6.

Even more terrifying was the "water inrush." The water at the west portal of the Snow Tunnel is deep "ancient groundwater" accumulated over 8,000 to 20,000 years 7. Once the water vein is broken, high-pressure water flows out like a flood, carrying mud and sand. The highest recorded water inrush volume reached 750 liters per second; such a scale of eruption could flood the tunnel and destroy any machinery in an instant 6.

To address these challenges, the project invested up to NT$100 million in preliminary alignment geological surveys and another NT$87.5 million in supplementary surveys during the construction phase, far exceeding the norms of domestic projects at the time 8.

Engineering Responses and Innovative Methods: The Resilience of Taiwanese People

Facing international experts who were at a loss, with some even declaring "if you can't solve it, commit seppuku" before leaving in disgrace 9, the Taiwan engineering team demonstrated astonishing resilience and innovation.

They created several "Five Major Methods" to cope with harsh geology 10, including:

  1. Three Shafts to Open Additional Working Faces: Three shafts (two main shafts and one adit shaft) were added in the middle section of the tunnel main line, excavating vertically from above to the tunnel depth to form multiple working faces for simultaneous construction, significantly shortening the construction period 1.
  2. Grouting Water Stop Technology: For high-pressure water inrushes, high-pressure grouting technology was used, injecting cement slurry or chemical grout into rock fractures to form a water-stop curtain, effectively controlling the water inrush 11.
  3. Pre-displacement Method: Reinforcing the surrounding rock in advance before excavation to reduce deformation and collapse after excavation.
  4. Advanced Geological Exploration: Using geological drilling and seismic methods to grasp the geological conditions ahead in advance and adjust construction strategies early.
  5. Combined Use of TBM and NATM: In the hard tetrahedral sandstone section, when TBM advancement was difficult, the team decisively switched to traditional NATM, and reactivated the TBM in more stable strata, flexibly responding to geological changes 3.

These innovative methods and flexible strategies ultimately allowed the Snow Tunnel project to overcome numerous difficulties.

Key Figures and Turning Points: From "Impossible" to "Full Line贯通"

The construction of the Snow Tunnel spanned multiple regimes and Premier terms, with each bearing the immense pressure of opening to traffic. This project tested technology, political commitment, and public patience.

On September 16, 2004, President Chen Shui-bian presided over the full-line breakthrough ceremony of the Snow Mountain Tunnel. In his speech, he lamented: "The engineering difficulty of the Snow Mountain Tunnel has been listed in the Encyclopedia Britannica; this is the asset of the entire nation" 12. Zheng Wenlong (Cheng Wen-lung), then Director of the National Highway Engineering Bureau, revealed a small secret behind the breakthrough ceremony: to ensure the blasting went smoothly on the day of the ceremony, engineering personnel had already "tampered with things" the day before, ensuring the last mile could be presented perfectly before the President and Vice President 13.

However, breakthrough did not mean the end. The subsequent improvement of electromechanical and traffic control systems took another two years. Then-Minister of Transportation Lin Ling-san (Lin Ling-san) faced immense political pressure due to multiple delays in inspection progress, even being mocked by legislators as "too realistic toward Premier Hsieh Chang-ting" 14. But for engineering personnel, safety was the only indicator; they insisted on opening to traffic only when safety was ensured.

The Names of 25 Martyrs: The Monument at Shih-keng Service Area

When we today blow air conditioning and listen to the radio in the tunnel, taking only about 40 minutes to cross the Xueshan Mountain Range, few notice a "Monument to the Martyrs of the Beiyi Highway Engineering" standing in a corner of the Shih-keng Service Area on National Highway No. 5.

This monument commemorates the 25 laborers who unfortunately died during the construction of the Beiyi Highway (including the Snow Mountain Tunnel). This includes 12 domestic engineers and 13 Thai laborers 15. Although there were 25 martyrs in the entire Beiyi Highway project, about 13 died directly in the Snow Mountain Tunnel project 16. Among them, some were buried under earth and rocks due to collapse, some were washed away by high-pressure water inrushes, and others died from overwork due to the harsh air and high temperatures in the tunnel.

The monument is made of the hardest "tetrahedral sandstone" in the Snow Mountain Tunnel, symbolizing the arduousness and challenges of the project. Its shape imitates the emblem of the National Highway Engineering Bureau and Guishan Island, with the names of all martyrs and engineering summaries engraved on the stele 8. These 25 lives are the heaviest footnote after the Snow Tunnel opened to traffic. The completion of this tunnel relied on engineering technology, but also on the risks borne by countless engineering personnel in the dark underground.

Yilan After Opening: The Cost and Harvest of the Third Revolution

The Snow Tunnel is called the "Third Revolution" in Yilan's development history 2.

  • First Revolution: 230 years ago, Wu Sha (Wu Sha) entered Yilan to reclaim land, opening the pioneering history of the Yilan Plain.
  • Second Revolution: Nearly a century ago, the railway from Taipei to Yilan opened, significantly improving transportation and material flow.
  • Third Revolution: On June 16, 2006, the Snow Mountain Tunnel opened to traffic, officially incorporating Yilan into the "Taipei One-Hour Commute Circle" 17.

After opening, Yilan's tourism and accommodation industry grew significantly, and housing prices soared, but it also brought serious weekend traffic congestion and social impacts such as the fragmentation of agricultural land. Records from the Yilan Grandma Story Museum mention that this tunnel made Yilan people "both eager and afraid of being hurt" 3.

Today's Snow Tunnel: Safety, Technology, and Challenges

The Snow Mountain Tunnel adopted world-class safety standards in its design, including a dual-bore one-way design to effectively avoid head-on collisions, and advanced electromechanical and disaster prevention systems 18 19. Its ventilation system is the world's first enhanced longitudinal flow system, equipped with 36 axial main fans and 112 jet fans, ensuring air quality and smoke exhaust efficiency in the tunnel 1.

However, since opening to traffic, the Snow Tunnel still faces challenges. Holiday traffic management is the biggest pain point; especially during Spring Festival and consecutive holidays, northbound traffic often increases by 10-24%, leading to severe congestion 20. The Highway Bureau has set up a slow-vehicle warning system and reminds road users through real-time video and broadcasting 20. Although the tunnel's safety design is excellent, the "Road Captain" phenomenon remains a key factor affecting traffic efficiency.

Data on the Snow Tunnel: Astonishing Numbers

The engineering scale of the Snow Mountain Tunnel was significant on the world map at the time:

Item Data Notes
Total Length Eastbound 12,871 meters / Westbound 12,947 meters Taiwan's longest highway tunnel 1
World Ranking Approximately 13th-15th Global highway tunnel length ranking, leading in Asia/Southeast Asia 21
Construction Period 15 years (1991-2006) Originally expected to be completed in 6 years 1
Total Budget Approximately NT$18.5 billion Only the Snow Tunnel section engineering cost 1
Opening Date June 16, 2006 Opened during Premier Su Tseng-chang's term 17
Maximum Speed Limit 90 km/h Relaxed to this in 2010 1
Number of Martyrs 25 (Beiyi Highway Project) / ~13 (Snow Tunnel Project) Includes domestic and foreign laborers 15 16
TBM Stuck Incidents 26 times TBM was stuck in the mountain for up to 885 days 6
Rockfall Incidents 63 times 6
Ventilation System 36 axial main fans + 112 jet fans World's first enhanced longitudinal flow 1
Lateral Links 36 pedestrian / 8 vehicle For emergency evacuation and rescue 1
Total Tunnel Complex Scale 58 tunnels Includes main tunnel, adit, link tunnels, etc. 1

Conclusion: A Flowing River of History

The Snow Mountain Tunnel is a hole of steel and concrete, but also a flowing history of engineering. With limited resources and international experts giving up, Taiwan engineers, relying on indomitable will and innovative thinking, completed this project hailed as an "impossible mission."

As Lian Yao-dong said, he once dreamed of the TBM falling into a black hole, and his soul had already been bound to this tunnel 2. This tunnel carries the most brilliant and painful memories of Taiwan's engineering community. Next time when you drive into the tunnel, watching the mile markers flashing on the wall, you might remember that afternoon in 1997, that figure risking his life to turn off the power in the darkness, and that group of unsung heroes fighting against millennia-old water inrushes in the mountain belly. Their stories are the scenery we should most remember when passing through the Snow Tunnel.

When passing through the Snow Tunnel, please slow down and respect traffic rules; this is responsible for your own safety and also for the blood, sweat, and tears contribution of the 25 martyrs and countless engineering personnel.

Further Reading

  • Taiwan Transportation System — Understand the transportation significance of the Snow Tunnel from highways, railways, and public transport networks.
  • Taiwan Urban Development and Urban-Rural Gap — Further reading on how transportation infrastructure changes local development and population flow.
  • Expressways — The Snow Mountain Tunnel is just a segment of Taiwan's 50-year national highway history; this article calculates the cost behind every "a little faster" from the Mai-Shen Highway to National Highway No. 7.

References

  1. Wikipedia: Snow Mountain Tunnel Entry — Provides background, data, or event context for this article, serving as a basis for item narration and verification.↩2345678910
  2. Li Cheng-chih (2021). . CTWANT: Blood and Tears Snow Tunnel 3 / Life Hanging by a Thread in the Tunnel, Overseas Chinese Engineer's Move Saved 300+ People — Provides background, data, or event context for this article, serving as a basis for item narration and verification.↩2345
  3. Yilan Grandma Story Museum: Penetrating the Mountain and Opening the Pass - Snow Mountain Tunnel — Provides background, data, or event context for this article, serving as a basis for item narration and verification.↩23
  4. Ministry of Transportation and Communications, Highway Bureau: National Highway No. 5 Engineering History — Provides background, data, or event context for this article, serving as a basis for item narration and verification.↩
  5. Yahoo News (2023): Listed in the Encyclopedia Britannica as the Most Difficult in History Snow Tunnel Blood and Tears History / 15 Years of Excavation Breaks Through Xueshan, Conquering Tetrahedral Sandstone Harder Than Steel — Provides background, data, or event context for this article, serving as a basis for item narration and verification.↩
  6. Fairy Tale Story (2006): [Diary] The Great Snow Mountain Tunnel Opens to Traffic Today — Provides background, data, or event context for this article, serving as a basis for item narration and verification.↩234
  7. Field Mountains and Forests (2013): The Unsung Heroes of the Beiyi Highway: Thirteen Years Underground — Provides background, data, or event context for this article, serving as a basis for item narration and verification.↩
  8. Rongmin Culture Network: Beiyi Highway Engineering Martyrs Monument — Provides background, data, or event context for this article, serving as a basis for item narration and verification.↩2
  9. Facebook (2023): Snow Tunnel Engineering Difficulty is Extremely High, World Miracle Listed in the Encyclopedia Britannica — Provides background, data, or event context for this article, serving as a basis for item narration and verification.↩
  10. Yahoo News (2023): Photo / Costing 1 Billion, the Excavation Artifact is Also Helpless! Snow Tunnel Opens as a World Engineering Miracle — Provides background, data, or event context for this article, serving as a basis for item narration and verification.↩
  11. Highway Bureau (2016): Topic Three Countries Five Snow Mountain Tunnel Construction Methods Review of Adjustments to Harsh Geology — Provides background, data, or event context for this article, serving as a basis for item narration and verification.↩
  12. Presidential Office Press Release (2004): President Attends the Full-Line Breakthrough Ceremony of the Beiyi Highway Snow Mountain Tunnel — Provides background, data, or event context for this article, serving as a basis for item narration and verification.↩
  13. Xin Yong Ge's Story (2018): Snow Mountain Tunnel Breakthrough Secret: Zheng Wenlong Talks 2004.9.16 — Provides background, data, or event context for this article, serving as a basis for item narration and verification.↩
  14. TVBS News (2006): Snow Tunnel Delayed Opening, Legislators: Lin Ling-san is Too Realistic Toward Premier Hsieh — Provides background, data, or event context for this article, serving as a basis for item narration and verification.↩
  15. Wikipedia: Monument to the Martyrs of the Beiyi Highway Engineering — Provides background, data, or event context for this article, serving as a basis for item narration and verification.↩2
  16. Taiwan Geological Knowledge Service Network (2006): Snow Tunnel Engineering is Difficult, 25 People's Blood and Tears Chronicle — Provides background, data, or event context for this article, serving as a basis for item narration and verification.↩2
  17. Executive Yuan Press Release (2006): Premier Su Tseng-chang Attends the Snow Tunnel Opening Ceremony — Provides background, data, or event context for this article, serving as a basis for item narration and verification.↩2
  18. Ministry of Transportation and Communications, Highway Bureau: Snow Mountain Tunnel Southbound 26K Traffic Accident Electromechanical System Improvement Project — Provides background, data, or event context for this article, serving as a basis for item narration and verification.↩
  19. CECI Engineering Consulting: Snow Mountain Tunnel Traffic Control System Improvement Enhances Accident Handling Efficiency — Provides background, data, or event context for this article, serving as a basis for item narration and verification.↩
  20. Ministry of Transportation and Communications, Highway Bureau (2023): National Highway No. 5 Snow Mountain Tunnel Traffic Management Strategy — Provides background, data, or event context for this article, serving as a basis for item narration and verification.↩2
  21. Wikipedia: List of World Highway Tunnels — Provides background, data, or event context for this article, serving as a basis for item narration and verification.↩
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