A drone steadily rises thru fog at the beginning of the video. Below, what looks to be a typical city street gradually reveals itself to be perched atop another street, which is perched atop a metro line that passes thru the center of an apartment building and backs onto a highway flyover that, at this angle, appears to be at the same level as the twenty-second floor of the tower across the gap. The camera continues to rise. There are more layers. The term “this doesn’t look real” appears repeatedly in the comments.
People have been subjected to this treatment by Chongqing for a number of years. The 34 million-person municipality, located where the Yangtze and Jialing rivers converge in the mountains of southwest China, has become the most popular urban spectacle on the internet. It is so physically peculiar that millions of people who have never heard of it are watching drone footage of its intersections at midnight and attempting to convince friends that, yes, a metro train actually passes thru floors six thru eight of a residential building. It’s an actual thing. The train departs on time. There is soundproofing for the residents. The structure dates back to 2005.
Almost unintentionally, TikTok captures the outcome of a city forced to construct differently. The flat river plain that is typically associated with Chinese urban development is not the landscape surrounding Chongqing. The metropolitan core is made up of mountains that are steep and irregular, with elevation fluctuations of at least 400 meters. A metropolis that was expanding at the same rate as Chongqing, taking in millions of rural migrants during its most rapid ten-year growth, was eager for flat terrain that didn’t exist. At the same time, it grew sideways and upward. The roads were piled high. Wherever the geometry permitted, transit lines were placed. Instead of being built next to the infrastructure, buildings were built around it. From above, it appears as tho someone attempted to construct a city on a crumpled sheet of paper and thot the crumpling was a feature.
The image that went viral was the Liziba Station sequence, where a nineteen-story residential structure is divided by Line 2 of the Chongqing Rail Transit. Rather than focusing on the building, it’s important to understand why it was constructed that way. Geology is the solution. The topography of Chongqing made it nearly impossible to locate a surface station without either demolishing the block or taking an unfeasible detour. The engineering approach was to go throughout it, incorporating vibration isolation and noise damping into the building’s floors as well as the station’s construction. The locals claim that they seldom notice the train. That might be both an engineering feat and a sign of how well humans have adapted to their built surroundings.
Pace, not design, is the real-life engineering challenge that the viral video alludes to but fails to completely explain. Between 2008 and 2020 alone, Chongqing constructed almost 300 towers. In less than 40 years, the city’s population increased from about three million to thirty-four million, a demographic shift so rapid that the infrastructure needed to support it has been catching up ever since. This is made more difficult by the geology: sinkholes have been reported in a number of areas as a result of construction loads stressing rock formations that were stable prior to the arrival of the city on top of the karst limestone that underlies much of the urban core. The water and sewage systems, which were built for a much smaller population, have been gradually extended beneath streets that are above other streets. This is a practical challenge that doesn’t look as good as the stacked roadways.
Kowloon Walled City is the uncomfortable analogy that springs to mind. It was both physically fascinating and physically perilous in ways that were tied to one another. This dense enclave of informal construction in pre-handover Hong Kong eventually housed some 33,000 people in 2.7 hectares, making it one of the most densely populated places ever documented. Because of the interdependence of the buildings, one’s structural stability relies on the support of others. Cascading failures might have resulted from a collapse. That degree of uncontrolled risk is not suggested by anything about Chongqing. However, the conditions that have historically produced engineering surprises include its rapid growth, the intricacy of its vertical layering, and the geological uncertainty beneath it. These are the kinds of conditions that are discovered later, sometimes much later, when something that was always there suddenly becomes readable.
In 1978, structural engineer William LeMessurier, who designed the Citicorp Center in Manhattan, found that the building’s columns were positioned at the midpoints of its structural faces instead of its corners. Due to this error, quartering winds, which strike buildings diagonally rather than directly, could produce a resonance pattern that was not taken into consideration in his initial calculations. The structure has been there for two years. Under some storm circumstances, it might have fallen within sixteen. Over the course of several months, the repair was made in secret at nite. New Yorkers passing by were unaware. LeMessurier’s shortcomings as an engineer were not the lesson. Sometimes, the combination of complexity, speed, and the boundaries of what any study can capture results in dangers that are only apparent after the fact.
