BEIJING, Oct. 2 (Xinhua) — China’s longest undersea highway tunnel marked the completion of all shield-driven excavation operations on Friday as a tunnel boring machine reached its designated receiving location at a depth of 105 meters below sea level in Jiaozhou Bay, east China’s Shandong Province, according to China Railway Construction Corporation Limited.
The Qingdao Jiaozhou Bay Second Tunnel will connect the primary urban core of Qingdao with the Qingdao West Coast New Area, a national-level development district. Spanning a total project footprint of 17.48 kilometers, the alignment features a 14.37-kilometer main subterranean segment configured with twin transit tunnels and a central auxiliary service bore, accommodating three traffic lanes in each direction at a designated operational speed of 80 km/h.
Wang Junping of China Railway 14th Bureau Group Corporation Limited noted that the engineering initiative deployed a combined methodology of drill-and-blast procedures and mechanized shield tunneling, driving simultaneously from the eastern and western shorelines of Jiaozhou Bay to complete a precision undersea breakthrough. The primary shield envelope reaches a maximum submarine depth of 95 meters below surface waters, while the auxiliary service passage extends to 105 meters, generating severe hydro-static pressure that mandated rigorous sealing criteria and structural waterproofing.
To mitigate operational bottlenecks and optimize performance under load, the engineering team deployed an integrated muck extraction architecture for the first time, consolidating a continuous screw conveyor, an integrated rock breaker housing, and primary rock-crushing units, Wang explained, adding that proprietary anti-vibration damping systems were developed specifically for the shield chassis to ensure dynamic structural stability.
Upon commissioning, the corridor will establish a tiered, multimodal cross-bay transit network for Qingdao alongside the operational Jiaozhou Bay Tunnel, Jiaozhou Bay Bridge, and Jiaozhou Bay Expressway.
The milestone coincides with national transport strategy: the Ministry of Transport announced in July that China launched an actionable framework to systematically accelerate the high-quality evolution of integrated transport operations across the 15th Five-Year Plan period (2026–2030). The policy directives target the substantive rollout of a modern, multi-tiered transport framework by 2030, emphasizing enhanced intermodal connectivity, seamless passenger transfer architectures, elevated logistics infrastructure, transportation-tourism synergies, and expanded rural freight, transit, and distribution systems.