Why Japan Built a $2.4 Billion Underground River Beneath Tokyo

How did Japan build a $2.4 billion underground river beneath Tokyo to protect thousands of homes from devastating floods? In this documentary, we explore G-Cans, an extraordinary flood-control system buried 50 meters underground. Discover how engineers built massive shafts, a 6.3-kilometer tunnel, a giant underground chamber supported by 59 pillars, and powerful pumps capable of moving 200 cubic meters of water per second. From the engineering challenges to Typhoon Hagibis in 2019, discover how this underground system helps protect Japan from flooding—and why even this incredible machine has its limits. #Japan #GCans #Engineering #Megaprojects #Tokyo #FloodControl #Infrastructure #Documentary Music credits (Ross Bugden - Olympus):    • ♩♫ Epic and Dramatic Trailer Music ♪♬ - Ol...