World’s Longest Underwater Tunnel Reaches Major Milestone in Qingdao: Key Details.

Northern Line Breakthrough Completed

According to ITC.ua — Техно: On July 14, 2026, workers in Qingdao, China, completed the excavation of the northern line for the second underwater road tunnel beneath Jiaozhou Bay. This achievement marks a critical step in building what will become the longest subsea tunnel on the planet. With a total length of 17.48 km—including 9.95 km running beneath the seabed—the project is setting new standards in underwater engineering.

The northern main tunnel section stretches 3,258 meters and features a boring diameter of 15.63 meters. The overall initiative is aiming for five world records, underscoring its scale and significance. Construction progress has already surpassed 70%, reflecting steady forward momentum.

Regional Transport Upgrades

For context, the first Jiaozhou Bay underwater tunnel opened in 2011 and measures 7.8 km. The new tunnel is scheduled to open for vehicle traffic in 2028, promising a major boost to local transportation networks. Beyond improving connectivity, this project presents a formidable technical challenge for engineers and builders alike.

The completion of the northern line represents a significant milestone in this ambitious infrastructure venture, which is expected to greatly enhance travel links between cities in the region. In addition to its engineering complexities, the tunnel reflects China’s broader push to develop modern infrastructure capable of meeting the growing demands of its population and economy. When finished in 2028, it could help establish new transport corridors and strengthen the region’s international competitiveness.