Shield tunneling

Shield tunneling is a method used to construct underground tunnels by using a large, special machine called a shield. This machine supports the ground around it as it gradually moves forward, while installing segments of tunnel lining to stabilize the excavated space. It's commonly used for subway lines, water, or utility tunnels in urban areas. The shield prevents surrounding soil or water from collapsing into the tunnel and allows construction to proceed safely beneath busy cities without extensive surface disruption. This technique is efficient, safe, and suitable for creating long, complex tunnels beneath the ground.