World's longest high-altitude tunnel at 3km above sea level cuts 7-hour journey in half

World's longest high-altitude tunnel at 3km above sea level cuts 7-hour journey in half Stretching 13.5 miles, the colossal tunnel forges its way through the complex Tian Shan Mountain range in northwest China's Xinjiang Uyghur Autonomous Region A high-altitude tunnel hailed as the world’s longest at more than 3,000 metres above sea level cuts a seven-hour journey in half by carving through a mountain range. Spanning 13.5 miles, the colossal Tianshan Shengli Tunnel forges its way through the Tian Shan Mountain range in northwest China's Xinjiang Uygur Autonomous $egion. China’s five-year project, part of the Urumqi–Yuli Expressway, aims to boost connectivity between the mountainous regions of northern and southern Xinjiang. It consists of two parallel tubes, each designed to carry two lanes of traffic. It's a considerable engineering feat, cutting through the central massif of the Tian Shan Mountains, one of Asia’s most complex ranges in terms of orography (referring to the height of the land). The enormous mountain range spans more than 2,500km. The tunnel reaches a maximum depth of over 1,100 metres below the mountain and crosses 16 geological fault zones."And there were further challenges, too. Workers would have faced extreme temperatures and heavy snow at altitudes above 3,000 metres. Engineers used specialist excavation equipment to cope with the weather, geological pressure and seismic activity. Previously, journeys through the region could take hours on treacherous roads exposed to everything from avalanches to snowstorms, but travellers can now make the trip in just 20 minutes. One clear example of the tunnel’s impact is the trip from Ürümqi to Korla - around 293 miles by road. It used to take more than seven hours, but reportedly now takes about 3 to 3.5 hours. The Tianshan Shengli Tunnel opened in December 2025. According to Song Hailiang, chairman of China Communications Construction Company (CCCC), it "set two world records". Song told state broadcaster CCTV: "It is the longest expressway tunnel in the world and has the deepest vertical shaft for a highway tunnel." Construction on the expressway got underway in April 2020 with 46.7 billion (£5.1bn) yuan pumped into the project. The tunnel was built at an altitude where temperatures can plunge to as low as -42°C. A retired doctor, Nurmanat Abdukader from Pishan county, told China Daily that he'd travelled to Urumqi for medical treatment and then waited until the expressway was complete to try it out. Nurmanat claimed that it had cut his trip home to a single day. It follows reports of an undersea tunnel costing £20billion that could cut an eight-hour journey to just 40 minutes. Also in China, the proposed Bohai Strait Tunnel is due to traverse several fault zones over its 123km (76-mile) length. Planners say it will also incorporate earthquake-resistant technology. A reported £20 billion is earmarked for the gargantuan project, but no firm date for its completion has been set. Despite this, a Chinese government representative said in 2018 that authorities were keen to launch "as soon as possible."i