The world's longest high-altitude tunnel, situated more than 3,000 meters above sea level, has halved a seven-hour journey by carving through a mountain range. Stretching 13.5 miles, the colossal Tianshan Shengli Tunnel forges its way through the complex Tian Shan Mountain range in northwest China's Xinjiang Uygur Autonomous Region.
Engineering Marvel in the Tian Shan Mountains
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. The tunnel is 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 2,500 kilometers. The tunnel reaches a maximum depth of over 1,100 meters below the mountain and crosses 16 geological fault zones.
Challenges Overcome
Workers faced extreme temperatures and heavy snow at altitudes above 3,000 meters. 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 travelers 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.
World Records and Construction
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 yuan (£5.1 billion) pumped into the project. The tunnel was built at an altitude where temperatures can plunge to as low as -42°C.
Impact on Travel
A retired doctor, Nurmanat Abdukader from Pishan county, told China Daily that he had traveled 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 £20 billion 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 123-kilometer (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."
