Chongqing Metro: The World’s Most Extreme Transit System

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Imagine commuting to work on a train that feels like a rollercoaster. It dives deep underground through solid rock, emerges high above a river on a towering bridge, and even passes straight through the middle of a high-rise apartment building. For millions of people in Chongqing, China, this isn’t a thrill ride at an amusement park. This is their daily commute.

The Chongqing Metro isn’t just another subway system. It’s one of the most complex and ambitious transit networks ever built, designed for a city where normal rules of urban planning simply don’t apply. Engineers were told the project was impossible. They built it anyway.

I’ve seen this network up close, and standing beneath a train line suspended hundreds of feet above a river is an experience you never forget.

The Mega City That Defies Gravity

To understand why this metro exists, you first need to understand the city it serves. Chongqing is a megacity of over 32 million people, nearly the population of Canada, and yet it remains relatively unknown outside China. It sits at the confluence of the Yangtze and Jialing rivers, surrounded by mountains and steep cliffs.

This city is often called the “8D City” a nickname that perfectly captures its extreme geography. Streets aren’t laid out in neat grids. Instead, they stack on top of each other at wildly different elevations. Some neighborhoods sit 200 to 300 meters apart vertically, which is like climbing a 70-story building just to reach the next street.

From certain vantage points, you can stand on one road and see another road floating far above you, like something out of a science-fiction movie. Building here has always been a challenge, but building mass transit in this terrain was once thought impossible.

Without a reliable transit system, daily life was chaotic. Before the metro, Chongqing ranked among China’s worst cities for traffic. Narrow mountain roads became gridlocked for hours during peak times. Buses crawled along at walking speed. Taxis were useless in heavy congestion. Expanding road capacity wasn’t an option because there was literally no space left to build.

The only solution was to go vertical, threading trains through mountains, rivers, and skyscrapers to keep the city moving.

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Why Chongqing Needed More Than Just a Subway

Most cities expand by adding wider streets or new highways, but Chongqing’s geography left no room for that. In some districts, engineers couldn’t even find flat land to build a traditional rail yard. Light rail and trams wouldn’t work either because the steep slopes and sharp turns exceeded their design limits.

The only realistic option was a metro system built to climb mountains and weave through impossibly tight 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 a key economic hub in western China. The government made a bold decision: invest billions into building a metro network unlike anything the world had ever seen.

A Network of Record-Breaking Engineering Feats

Today, the Chongqing Rail Transit (CRT) system spans over 560 kilometers of track, making it the sixth-longest metro network on Earth. That’s longer than the entire subway systems of New York or London. And it’s still expanding at remarkable speed.

But the sheer size of the network isn’t what sets it apart. Its vertical complexity is unmatched.

• Hualongqiao Station sits on a platform 50 meters above ground, supported by towering concrete pillars rising out of a steep riverbank.
• Hongyancun Station, which opened in 2022, plunges 116 meters underground, making it the deepest subway station in Asia. It takes nearly eight minutes on an escalator to reach the surface.
• Liziba Station has become an internet sensation because the trains literally pass through the 8th and 9th floors of an apartment building. Engineers reinforced the structure with vibration isolation systems so residents barely feel a rumble when a train passes. Inside, the noise level stays below 60 decibels quieter than a normal conversation.

Bridges are another highlight of this system. The Egongyan Suspension Bridge carries trains and road traffic on separate decks, while the Chaotianmen Bridge, one of the world’s longest arch bridges, supports heavy metro lines spanning the Yangtze River. These megastructures aren’t tourist attractions they’re part of everyday commuting.

Every line in this network tells a story of problem-solving at the limits of engineering.

The Breakthrough: Building a Metro Where None Should Exist

Early proposals to build a subway in Chongqing date back to the 1940s, but every plan failed for the same reason: the terrain was too difficult. Standard subway tunneling methods couldn’t handle the steep inclines and rapid elevation changes.

By the 1990s, the city’s population was booming, and the government faced an urgent crisis. That’s when a radical idea emerged: use monorail technology instead of traditional heavy rail.

Monorails are ideal for mountainous cities because they require less space, can climb steeper slopes, and handle tight curves more easily. Chongqing partnered with Japanese companies like Hitachi, adapting monorail technology to local conditions.

Engineers even invented custom machines for the project. One of the most important was a beam-laying machine that could operate on narrow streets and steep terrain where normal cranes couldn’t fit.

In 2005, Line 2 opened to the public, featuring the now-famous Liziba Station. The line was an immediate success, proving that monorails could solve Chongqing’s unique transit challenges.

Since then, the system has exploded in size. Today, it operates 12 lines, combining monorail segments with conventional heavy rail. Three more lines are under construction, and by 2035, the city plans to have 23 lines totaling more than 1,000 kilometers of track. That’s more metro track than the entire country of Germany.

Engineering Wonders Beneath and Above the City

Some of Chongqing’s metro construction feats border on the unbelievable.

• Hongyancun Station, the deepest in Asia, required 30 years from initial planning to completion. Workers spent months climbing down 20 minutes each day to reach the excavation site at the bottom of the shaft. Engineers had to manage extreme water pressure, ensure proper ventilation, and design emergency escape routes for both passengers and workers.
• For stations built into cliffs, like Hualongqiao, engineers had to design special retaining structures to prevent landslides during construction.
• Advanced noise-reduction technology was integrated into lines passing through residential buildings, proving that infrastructure and urban living can coexist.

Chongqing’s metro has also become a model for transit-oriented development. Many stations are integrated with shopping centers, office complexes, and residential towers, creating compact neighborhoods that reduce reliance on cars.

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Looking Ahead: A City and Metro Still Growing

Chongqing’s metro moves over 3 million passengers per day, with peak daily ridership surpassing 4.2 million during major holidays. As the city continues to grow, so will its network.

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

This isn’t just about transportation. It’s about keeping one of the world’s most complex cities alive and thriving.

Final Thoughts

The Chongqing Metro is more than a transit system. It’s a living monument to human determination and engineering ingenuity. Built through mountains, under rivers, and even inside buildings, it proves that no challenge is too great when a city refuses to accept the word “impossible.”

I’ve stood in a station deep beneath a mountain here and watched as trains whisked thousands of people to work and back home again. It’s an awe-inspiring sight a reminder of what can be achieved when necessity drives innovation.