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Tokyo is one of the busiest cities in the world. But few people know that this famous city is situated on a complex of buildings.architectureUnderground. With foresight and superb engineering, the Japanese built a massive underground drainage system near the capital.
Deep beneath the city of Saitama, on the outskirts of Tokyo, lies a massive drainage system. This structure was built to protect the city's 13 million residents from heavy rains and increasingly severe tropical storms that frequently strike Japan.
The full name of this project is "Metropolitan Area Outer Underground Discharge Channel," but it is commonly referred to as G-Cans.
This massive complex of tunnels was constructed between 1992 and 2006, costing nearly $3 billion (approximately VND 62.4 trillion). The project consists of five concrete storage chambers, each 65 meters high and 32 meters in diameter, connected by tunnels spanning 6.4 kilometers.
Next to it is a large water tank, 25.4m high, 177m long, and 78m wide, known as "The Temple." Supporting this crucial water tank are 59 large pillars connected to 10 high-capacity pumps capable of pumping up to 200 tons of water into the Edogawa River every second.
The structure itself is a marvel of modern engineering. The idea behind this project is actually quite simple: to divert all the rainwater from storm surges, tropical cyclones, and floods from surrounding cities and towns, especially Tokyo, into the Edogawa River.
This aims to minimize the damage that floods can cause, such as the destruction of homes and important buildings.
The enormous "Underground Temple" pool is the most impressive highlight of the entire area. With its massive size and unique design, this colossal structure has been used as a backdrop in numerous television series.
Floodwater from the city's water pipes would flow through the tunnels and into the reservoir. When the reservoir was full, the water would travel through long tunnels before eventually flowing into this massive "underground temple."
From here, four jet-powered turbines will perform their task, pumping 53,000 liters of water per second out into the Edogawa River.
The benefits of this massive drainage system are a subject of much debate. Questions have been raised about the legality of the system, as well as doubts about whether it will actually function as intended.
Another issue raised is its current usability, given that the sole purpose for which this massive structure was built is for "super-disasters."
This leaves many wondering whether the entire project is wise and ahead of its time, or simply a "lucrative opportunity" for construction companies.
According to the Tokyo Disaster Management Center, if a total rainfall of approximately 550mm falls on Tokyo over three consecutive days, causing the Arakawa River to overflow, up to 97 subway stations could be completely submerged.
That is precisely the scenario that G-cans were built to address. However, the aforementioned scenario is a once-in-200-years event and extremely rare. Therefore, currently, G-cans remains only a gigantic, abandoned underground structure.
Whether or not it's actually a "secret weapon," the G-cans project remains an incredible structure with a strange and unique beauty. Because of this, it has become a popular tourist destination.
When not performing their drainage function, these tunnels become tourist attractions four days a week. Standing 50 meters underground, with the sounds of air compressors and dripping water echoing in the distance, is truly a fascinating experience.
