Second Jiaozhou Bay undersea tunnel: How engineers beat the pressure beneath the sea
Source：CCCCTime：2025-09-12
Once completed, the tunnel will reduce travel time between Huangdao and Qingdao to just 15 minutes.
Did you know? In building Qingdao's second Jiaozhou Bay undersea tunnel, every patch of tunnel wall the size of a human hand must withstand the weight of a one-ton truck. Join us as we look inside this mega project to see how CCCC engineers are carrying out their "voyage beneath the sea" under extreme water pressure.
The tunnel stretches 17.48 km, including a 9.95 km undersea section—making it the longest highway tunnel beneath the sea anywhere in the world. At the World Tunnel Congress 2024, the project was named one of the 50 iconic projects in global tunneling and underground engineering.
Using the mega shield tunneling machine, CCCC engineers drove through massive fault zones, overcoming world-class challenges in extreme conditions.
They enhanced the strength and durability of tunnel segments to keep seawater firmly at bay, and developed a supercomputing system that monitors every key parameter of excavation with precision, ensuring both safety and efficiency.
A fully integrated slurry–storage–grouting system, like a self-sustaining "factory" for the shield machine, cut down tunnel transport needs and boosted productivity by about 15%.
Meanwhile, advanced tools including AI, 5G, BIM, digital twins, and IoT created a digital construction platform deep beneath the seabed, enabling real-time insights into progress.
Once completed, the tunnel will reduce travel time between Huangdao and Qingdao to just 15 minutes, accelerating integration across Jiaozhou Bay's eastern and western shores.
Editor: First Highway Engineering
