China Completes World's Largest Underwater Road Tunnel in Record Time.

China has achieved a remarkable engineering milestone by completing the underwater section of the Jinan Huanggang Road Yellow River Crossing Tunnel in just 110 days. Spanning 5,755 meters (approximately 3.6 miles), with a 3,290-meter (2-mile) underwater shield segment, this tunnel boasts a diameter of 17.5 meters (57.4 feet), making it the world's largest-diameter underwater shield tunnel.

Excavation commenced on September 1, 2024, utilizing the "Shanhe" tunnel boring machine (TBM), a state-of-the-art mixshield TBM developed in Jinan. The "Shanhe" advanced at a rate of 16 to 18 meters (52.5 to 59 feet) per day, setting a new world record for 17-meter-class shield construction. The TBM's cutting-edge features include a pressurized composite cutter head, retractable main drive, and an intelligent equipment system that allows for real-time monitoring and remote operation.

The tunnel's innovative single-tube, double-deck design accommodates three lanes in each direction, optimizing space and reducing costs by approximately 15% compared to conventional twin-tube tunnels. Once completed, vehicles will traverse the tunnel at speeds up to 60 km/h (37.2 mph).

 This monumental infrastructure project is expected to significantly enhance transportation efficiency in the region, providing a direct route for commuters and freight, alleviating congestion on existing bridges, and fostering economic integration across the Yellow River’s banks. The tunnel is scheduled to be fully operational by late 2025.