Imagine taking a train to and from work, feeling like you're on a roller coaster. It passes through hard rock, goes underground, crosses rivers along towering bridges, and even directly through the center of high-rise apartment buildings. For millions of people in Chongqing, China, this isn't an amusement park ride. This is their daily commute.

Chongqing Rail Transit is not just a regular subway system. It is one of the most complex and ambitious transportation networks ever built, designed for a city where conventional urban planning rules simply don't apply. Engineers were told the project was impossible, but they built it anyway.

Standing under the train tracks hundreds of feet above a river is an unforgettable experience.

Gravity-defying Mega City

To understand the significance of this rail network, we first need to understand the city it serves. Chongqing is a megacity with over 32 million people, almost as many as Canada's population, yet it is relatively unknown outside of China. It is located at the confluence of the Yangtze River and the Jialing River, surrounded by mountains and steep cliffs.

The city is often called the "8D City," a nickname that perfectly captures its extreme geography. Streets are not laid out in a neat grid, but instead are stacked at vastly different elevations. Some neighborhoods have vertical distances of up to 200 to 300 meters, akin to climbing a 70-story building to reach the next street.

From certain vantage points, you can stand on one road and see another road floating high above, like a scene from a science fiction movie. Building roads here has always been a challenge, but building a public transportation system in such terrain was once considered impossible.

Without a reliable transport system, daily life would be chaotic. Before the subway was built, Chongqing was one of the worst-connected cities in China. Narrow mountain roads would get stuck in traffic for hours during rush hour. Buses moved so slowly that they were barely faster than walking. Taxis were useless in traffic jams. Expanding road capacity was impossible because there was hardly any space left for construction.

The only solution was to build vertically, allowing trains to go through mountains, rivers, and skyscrapers to keep the city running.

Why Chongqing Needs More Than Just a Subway

Most cities expand by widening streets or building new highways, but Chongqing's location doesn't allow that. In some areas, engineers couldn't even find flat ground to build traditional railway stations. Light rail and tram systems couldn't operate because the steep slopes and sharp curves exceeded their design limits.

The only realistic option was to build a subway system capable of crossing mountains and navigating extremely narrow urban spaces. Without it, Chongqing's growth would stall, and its economy, driven by manufacturing, logistics, and finance, would suffer.

The stakes were high. By the late 1990s, Chongqing had become an important economic hub in western China. The government made a bold decision: invest billions of dollars to create an unprecedented rail network.

A Record-Breaking Engineering Network

Today, the Chongqing Rail Transit (CRT) system is over 560 kilometers long, making it the sixth-longest rail network in the world, longer than the combined subway systems of New York or London. And it continues to expand at an astonishing rate.

But its size is not what makes it unique. Its vertical complexity is unparalleled.

  • The Hualongqiao Station is located on platforms 50 meters above the ground, supported by towering concrete pillars rising from steep riverbanks.
  • The Hongyan Village Station, which opened in 2022, is 116 meters deep underground, making it the deepest metro station in Asia. It takes nearly 8 minutes to reach the surface using escalators.
  • The Liziba Station became a popular spot on the network because the train passes directly through the eighth and ninth floors of an apartment building. Engineers reinforced the station structure and installed vibration isolation systems, so residents feel almost no noise when the train passes. The noise level inside the station remains below 60 decibels, lower than normal conversation.

Bridges are another highlight of the system. The Egongyan Suspension Bridge features a dual-deck design, carrying both trains and road traffic; while the Chaotianmen Bridge is one of the longest arch bridges in the world, supporting the metro line that spans the Yangtze River. These massive structures are not tourist attractions, but part of daily commutes.

Every line in this network tells a story of solving problems at the edge of engineering possibilities.

Breakthroughs: Building Subways Where They Shouldn't Exist

Early plans for building subways in Chongqing date back to the 1940s, but all failed for the same reason: the terrain was too complex. Traditional subway tunneling methods could not handle the steep grades and rapid elevation changes.

By the 1990s, the city's population exploded, and the government faced an urgent crisis. At that time, an unconventional idea emerged: replacing traditional heavy rail with monorail technology.

Monorails are ideal for mountainous cities because they take up less space, have better climbing ability, and can make tighter turns. Chongqing partnered with Japanese companies like Hitachi to adapt monorail technology to local conditions.

Engineers even invented custom machines for the project. One of the most important inventions was a beam-laying machine that could operate in narrow streets and steep terrains where ordinary cranes couldn't reach.

In 2005, Line 2 officially opened, bringing the iconic Liziba Station with it. The line was an immediate success, proving that monorail transport could effectively solve Chongqing's unique traffic challenges.

Since then, the system has expanded rapidly. Today, it operates 12 lines, combining monorail sections with traditional heavy rail. Three more lines are under construction, and by 2035, the city plans to have 23 lines with a total length of over 1,000 kilometers. That’s more than the entire German subway network combined.

Engineering Marvels Above and Below the City

Some of Chongqing's rail transit achievements are simply incredible.

  • The Hongyan Village Station is the deepest station in Asia, taking 30 years from initial planning to completion. Workers spent months descending 20 minutes each day to reach the excavation site at the bottom of the shaft. Engineers had to control extremely high water pressure, ensure proper ventilation, and design emergency escape routes for passengers and workers.
  • For stations like Hualongqiao, which are built on cliffs, engineers had to design special retaining structures to prevent landslides during construction.
  • Lines passing through residential buildings use advanced noise-reduction technology, proving that infrastructure and urban life can coexist.

Chongqing Rail Transit has also become a model for transit-oriented development. Many stations are integrated with shopping centers, office buildings, and residential complexes, forming compact communities that reduce reliance on cars.

Looking Ahead: The City and Its Rail Network Keep Growing

Chongqing Rail Transit carries more than 3 million passengers daily, with peak passenger numbers exceeding 4.2 million on major holidays. As the city continues to grow, its metro network will keep expanding.

Future expansions aim to connect remote mountainous areas and industrial zones, while relieving pressure on the city center. The government has also begun exploring autonomous train technology and smart signaling systems to improve safety and efficiency.

This is not just about transportation—it's about keeping one of the world's most complex cities alive and prosperous.

Last Thoughts

Chongqing Rail Transit is more than just a transportation system; it is a living monument to human determination and engineering ingenuity. It goes through mountains, under rivers, and even inside buildings, proving that any challenge can be overcome if a city dares to face the "impossible."

Standing in the station at the foot of the mountains, watching the trains carry thousands of people to and from work—this sight is amazing and reminds us of what can be achieved when demand drives innovation.

Sources: Amazing Construction

Original: https://www.toutiao.com/article/7548625071397487155/

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