Tianshan Shengli tunnel transforms routes beneath Xinjiang’s mountains

High in Central Asia’s icy mountains, a newly built structure of concrete and steel is quietly altering the map of mainland China.

Located far from Beijing and Shanghai, the project lies in a region that for many years remained on the country’s margins. This new tunnel, driven through Xinjiang’s Tian Shan range, may transform trade routes, cut hours from road journeys and project Beijing’s ambitions well beyond China’s frontiers.

The Tianshan Shengli tunnel, a record beneath the mountains

China’s Tianshan Shengli tunnel extends for 22.13 km beneath the Tian Shan, a formidable mountain chain widely regarded as one of Asia’s most challenging construction environments. As the central feature of Xinjiang’s Ürümqi–Yuli expressway, it connects the region’s north and south in about 20 minutes, replacing journeys that previously lasted several hours.

Construction teams encountered high-pressure shifting rock, winter temperatures well below freezing and erratic groundwater. Engineers tackled these conditions using powerful tunnel-boring machines, intensive rock monitoring and multiple layers of digital supervision.

The tunnel runs in two separate tubes, each carrying two lanes, with continuous monitoring, automated emergency exits and controlled ventilation designed for heavy traffic in a hostile environment.

China describes the route as the world’s longest highway tunnel in operation, surpassing existing European and Japanese tunnels while remaining shorter than projects that are still being built.

Engineering under extreme conditions

Working beneath the Tian Shan is very different from excavating softer, lower mountains in coastal areas. Seasonal temperatures fluctuate dramatically, while snow and ice can limit access to construction sites. Rock layers deep underground are subject to intense stress, creating the potential for sudden collapses.

To protect both construction workers and future motorists, managers installed an extensive network of sensors throughout the tunnel. The equipment monitors rock displacement, humidity, temperature and air quality. Information is transmitted to a continuously staffed central control room, allowing operators to alter ventilation, lighting and traffic restrictions within seconds.

Key safety features include:

• Two parallel tubes, each with two lanes, separated to limit collision risk
• Cross passages at regular intervals for evacuation during incidents
• Jet fans and air-quality sensors to manage exhaust and smoke
• Automatic fire detection and firefighting systems tuned for long tunnels
• Real-time video surveillance and speed management

The build also trialled new methods of ground treatment. In unstable areas, workers injected grout into fractures before excavation began. In sections with heavy water inflows, they installed drainage galleries and waterproof linings to stop leaks from bubbling onto the carriageway years later.

The technical goal went beyond “breaking through” the mountain; engineers aimed for infrastructure that can run safely for decades under high traffic loads and harsh weather.

Rewiring Xinjiang, from isolation to connection

From distant frontier to inland crossroads

For many decades, Xinjiang was distant from China’s fast-growing coastal centres in more than geographical terms. Travelling between northern cities such as Ürümqi and communities further south often required winding routes over mountain passes or lengthy detours around them. Severe weather could shut roads for days at a time.

The Tianshan Shengli tunnel alters that situation. Journeys across the mountain barrier now fall from several hours to around 20 minutes. Freight operators can work to narrower delivery schedules, while bus services can introduce direct connections that previously appeared impractical.

Residents can reach major hospitals, universities and administrative facilities in Ürümqi more quickly. Logistics, e-commerce and energy businesses can also design supply chains on the basis that northern and southern Xinjiang form one market, rather than two separate areas.

The engineering achievement also carries a political message. Beijing promotes the expressway as part of a “balanced development” strategy intended to encourage inland growth and tie remote areas more closely to the national centre.

Economic corridors and the Belt and Road effect

The Ürümqi–Yuli expressway is one element of the wider land-based network associated with China’s Belt and Road Initiative. Xinjiang is positioned at the point where Chinese road and rail infrastructure runs west towards Kazakhstan, Uzbekistan and, through connected routes, Europe.

By reinforcing a key domestic route that feeds into international corridors, the tunnel supports that strategy. Improved internal connections allow trains and lorries to travel from Chinese factories and inland warehouses to Central Asian border crossings with fewer hold-ups and more predictable costs.

By smoothing the flow of people and goods inside Xinjiang, the tunnel adds another brick to an emerging Eurasian land bridge, partly bypassing sea lanes controlled by rival naval powers.

For European importers, this could eventually provide further rail and road choices for particular products, including electronics, textiles, machine components and time-sensitive consignments positioned between air freight and sea shipping in both cost and speed.

China’s long list of headline projects

A pattern of building in difficult places

The Tianshan Shengli tunnel becomes part of a wider collection of Chinese megaprojects intended to extend technical capabilities in severe environments. Chinese officials frequently point to examples including:

• The Hong Kong–Zhuhai–Macao Bridge, stretching across the Pearl River estuary with long-span bridges and an immersed tunnel
• High-speed rail lines crossing permafrost, earthquake zones and high plateaus
• Deep railway tunnels in Tibet where altitude and geology challenge standard methods
• Offshore energy platforms in the South China Sea

One notable earlier example was Xiamen North railway station, which engineers shifted sideways by approximately 300 metres using hydraulic jacks rather than demolishing and rebuilding it. Chinese state media portrayed the operation as evidence of a new level of engineering confidence.

The Tian Shan scheme follows this same narrative. Officials present it as evidence that China can overcome difficult terrain domestically and undertake comparable projects overseas, from South-East Asia to the Middle East and Eastern Europe, often through Belt and Road contracts.

Global tunnel rankings: where Tianshan Shengli stands

Tunnels have long been a measure of national engineering ambition. Norway, Switzerland and Austria have each constructed major mountain links to connect isolated areas and maintain trade through winter storms. By length, the new Chinese tunnel now ranks among the leading examples.

The order will change when Norway’s Rogfast, planned to reach 26.7 km, opens in the next decade. Until then, China has gained another entry on the global infrastructure scoreboard.

Safety, risk and what long tunnels mean for drivers

Record-breaking infrastructure inevitably prompts concerns about risk. Once a highway tunnel exceeds 20 km, it functions as a system in its own right rather than simply a passage through rock. Air quality, lighting, driver behaviour and emergency response interact in complex ways.

The designers of Tianshan Shengli had to account for several situations:

• Vehicle fires and smoke spread in confined space
• Breakdowns or collisions far from daylight exits
• Driver fatigue and monotony in long, uniform sections
• Loss of power or communication deep underground

To lower these risks, the tunnel provides bright and even illumination, avoiding abrupt changes that could distract motorists close to the portals. Gentle bends and road markings are intended to help drivers remain attentive. Emergency bays and telephones are provided at short intervals, while regular exercises prepare staff to direct evacuations through passages connecting the two tubes.

For motorists, the most significant change in behaviour is often preparation. Keeping a reasonably full fuel tank, checking ventilation settings and watching signs carefully can have a meaningful effect in long tunnels, especially in places where underground mobile reception may be weaker.

Beyond Xinjiang: what this means for future projects

Experience from the Tian Shan will inform a second generation of exceptionally long tunnels around the world. Data collected from millions of vehicle trips will indicate where congestion develops, how drivers react to information messages and which safety systems provide the quickest response.

Nations preparing their own megaprojects, from subsea connections in Scandinavia to transalpine routes in Europe, will be observing closely. Chinese contractors, meanwhile, can cite Tianshan Shengli as a reference project when competing for overseas work, arguing that they have already managed comparable distances and hazards in demanding mountain conditions.

For infrastructure students, the tunnel provides a practical illustration of ideas including rock stress, redundancy and network effects. Reducing travel time through a single mountain range can affect entire trade routes, alter warehouse locations and even shape where new towns expand. Such a sequence of effects often begins with choices made years beforehand by surveyors, geologists and engineers examining an isolated ridge in winter cold.