New 5,291-ton tunnel machine spans 54.7 feet and can handle steep curves

In Zhengzhou, China's largest tunnel boring machine was completed: diameter 16.7 m, length about 125 m, mass 5,291 tons. The machine is designed for pressures up to 8 bar and can handle steep curves and slopes; it will be used for underwater and urban tunnels.

• Boring diameter — 16.7 m, length — about 125 m, mass — 5,291 tons
• Operates at pressures up to 8 bar, cutters changeable without pressure release
• Slurry pump and crusher outside the chamber reduce underwater repair risk
• Being prepared for first high-speed tunnel under the Yangtze at 107 m depth