Do you know any famous tunnel engineering projects? Here are the top ten tunnel engineering projects in the world:

　　1. Gotthard Tunnel:

　　Location: In the Swiss Alps, crossing the Gotthard Pass.

　　Features: With a total length of 57.09 km, it is the world's longest railway tunnel, designed with twin tubes providing two separate tunnel passages.

　　Construction Challenges: It traverses hard rock geology, requiring solutions for high pressure and high temperature environments, using TBM (Tunnel Boring Machine) technology.

　　Significance: Improves north-south traffic in Europe, reduces travel time, and significantly boosts regional economic development.

　　2. Channel Tunnel:

　　Location: Connects the UK and France, crossing the English Channel.

　　Features: With a length of 50.45 km, it is the world's longest underwater tunnel, designed for rail, linking high-speed train services between the two countries.

　　Construction Challenges: Faced high-pressure water, complex geological structures, and extreme weather conditions, utilizing advanced shield technology and tunnel lining systems.

　　Significance: Enhances transportation and economic exchange between the UK and France, reducing cross-border travel time.

　　3. Seikan Tunnel:

　　Location: Between Honshu and Hokkaido in Japan, crossing the Tsugaru Strait.

　　Features: With a total length of 53.85 km, it is the world's longest rail and road tunnel, with an underwater section of 23.3 km.

　　Construction Challenges: Dealt with complex geological conditions, including seabed sediments and volcanic activity areas, using a combination of shield and drilling-blasting methods.

　　Significance: Strengthens the connection between Honshu and Hokkaido, significantly impacting local economy and transportation.

　　4. Turin-Milan High Speed Rail Tunnel:

　　Location: Italy, connecting the cities of Turin and Milan.

　　Features: Approximately 35.5 km long, it is Italy's longest high-speed rail tunnel, utilizing advanced tunnel lining and ventilation systems.

　　Construction Challenges: Crosses the pre-Alps, requiring solutions for safety issues in highland tunnel construction.

　　Significance: Significantly reduces travel time between Turin and Milan, enhancing transportation efficiency in northern Italy.

　　5. Laerdal Tunnel:

　　Location: Norway, connecting Oslo and Bergen.

　　Features: At 24.51 km, it is the world's longest road tunnel, featuring complex ventilation systems and emergency shelters.

　　Construction Challenges: Crosses hard rock layers, needing solutions for large-scale drainage and ventilation issues, employing TBM technology.

　　Significance: Improves traffic safety and convenience in western Norway, positively impacting local tourism and economic development.

　　6. Gotthard Road Tunnel:

　　Location: Switzerland, part of the Alpine highway.

　　Features: Approximately 17.1 km long, it is the world's longest road tunnel, designed with twin tubes providing two separate tunnel passages.

　　7. Eastern Suburbs Railway Tunnel:

　　Location: Sydney, Australia, part of the city's metro system.

　　Features: At 15.5 km, it is Australia's longest rail tunnel, using shield technology to traverse Sydney's complex urban geology.

　　Construction Challenges: Required construction in a busy city center while avoiding impacts on surrounding buildings and infrastructure.

　　Significance: Relieves traffic pressure in Sydney's urban area, improving public transportation efficiency and contributing to long-term urban development.

　　8. Dali-Ruili Railway Tunnel:

　　Location: Yunnan Province, China, a key control project of the Dali-Ruili Railway.

　　Features: Approximately 14.5 km long, it is the longest railway tunnel in southwest China, crossing the Hengduan Mountains.

　　Construction Challenges: Faced high altitudes, complex geology, and harsh climate conditions, using a combination of TBM and drilling-blasting methods.

　　Significance: Essential for completing the railway network in southwest China, promoting local economic development.

　　9. Qingma Bridge and Tunnel:

　　Location: Hong Kong, connecting Kowloon Peninsula and the New Territories.

　　Features: Approximately 13.4 km long, including both the Qingma Bridge and tunnel parts, serving as a major traffic artery in Hong Kong.

　　Construction Challenges: Required solutions for deep-water construction and complex geological conditions, employing advanced bridge and tunnel construction technologies.

　　Significance: Greatly improves transportation in Hong Kong, promoting regional economic development.

　　10. Dazhushan Tunnel:

　　Location: Dali, Yunnan, connecting Dali and Ruili.

　　Features: Approximately 14.5 km long.

　　Construction Challenges: Encountered various risks such as complex fault zones, water and mud inrush, weak surrounding rock deformation, high geothermal heat, and rock bursts. The geological conditions are extremely complex and variable, with water inrush filling a West Lake every three months. Only 156 meters were excavated in 26 months; construction began in 2008 and is still ongoing.

　　Significance: Once completed, the Dali-Ruili Railway will revive the ancient Southern Silk Road, highlighting Yunnan's role as a bridge to Southeast and South Asia, significantly promoting the economic and social development of the regions along the route.