World's longest tunnel costing £20bn set to cut eight-hour journey down to 40 minutes

A revolutionary undersea tunnel costing £20billion could slash a eight-hour journey down to just 40 minutes. The planned Bohai Strait Tunnel in China will pass through several fault zones over its 123km (76 mile) length, and planners say they will implement advanced earthquake-resistant technology to guard against disaster. The design incorporates longitudinal ventilation shafts to manage air quality across the massive distance. There are also dozens of cross-passages between the two parallel tunnels, which are set to extend about 80m below the sea floor. The designers have also allowed for several hundred emergency refuge areas, crucial for evacuation in a 123-km tunnel where fire or flood could be catastrophic. The current working budget for the groundbreaking project is an estimated £20billion, and while no firm date for the tunnel’s completion has been announced a Chinese government representative stated in 2018 that authorities were eager to launch the project "as soon as possible." The tunnel, when it is eventually completed, will dwarf all of its existing rivals. The 31-mile (49.6 km) Channel Tunnel was first mooted during the Napoleonic Era but was only completed in 1993. The 53.85-kilometre (33.5-mile) Seikan Tunnel in Japan is the world's longest tunnel that runs under a body of water, with with an undersea stretch of 23.3 km (14.5 miles). The Bohai Strait Tunnel’s trains are set to run at speeds of over 150mph and will slash the travel time between the cities of Dalian and Yantai by nearly 90%. They'll outpace Eurostar trains, which only hit 100mph when using the Channel Tunnel. A whopping 56 miles of the tunnel would be submerged, surpassing the combined lengths of the Channel Tunnel and the underwater section of the Seikan Tunnel. This incredibly ambitious project is predicted to take between 10 and 15 years to finish. For comparison, it took roughly six years to complete the Channel Tunnel after ground was eventually broken. The first train through the tunnel would likely run some time in the late 2030s or beyond. The cities at each end of the tunnel are crucial industrial powerhouses. Dalian has grown from a significant port into a leading financial, shipping and logistics hub for East Asia. Meanwhile, Yantai, traditionally celebrated for its fruit cultivation, has recently witnessed substantial growth in petrochemicals, automotive manufacturing, electronics, pharmaceuticals and cutting-edge tech sectors. At present, the quickest link between the two cities is the Bohai Train Ferry, which requires roughly eight hours to traverse the strait. By dramatically reducing the journey time between the cities, Chinese officials aim to boost their expanding economic output. A government representative stated in 2018 that authorities were eager to launch the project "as soon as possible." Lu Dadao, from the Chinese Academy of Sciences, informed journalists that a tunnel beneath the Bohai would revolutionise transport networks across China. They said: "By avoiding the hubs in Beijing and Tianjin it would relieve pressure on railways between Beijing and Tianjin, Beijing and Shanghai, and even Beijing and Guangzhou." Du Yanliang, from the Chinese Academy of Engineering Sciences, explained to ThePaper that the tunnel would also forge stronger links between the north-east's traditional industrial heartlands, the Bohai economic zone and the Yangtze delta region. The scheme hasn't been without its critics, though, with green campaigners highlighting that the region teems with wildlife, particularly serving as a crucial habitat and breeding ground for the spotted seal, a Class 2 protected species. Multiple zones within the planned construction area have been identified as possible locations for nature reserves. Sun Fenghua from the Chinese Academy of Sciences has emphasised the importance of "serious research into all issues associated with construction of the tunnel... We must not proceed until these questions are fully understood."