Meet Jianghai: China's Giant Tunnel-Boring Machine

Imagine a machine that can dig a tunnel wide enough to fit a five-story building through it. That's exactly what China has built! This machine, named Jianghai, is the country's largest tunnel-boring machine (TBM). It weighs a whopping 5, 000 tons and is 16. 64 meters in diameter. Why is this a big d