The Yangtze River Delta, China's most economically developed region, has long had one major weakness: its coastal transport network forms a "C" shape, with a gap around the Zhoushan Archipelago, China's largest group of islands.

In recent years, however, a mega island-linking project has been closing that gap, connecting Ningbo to the south with Shanghai to the north and gradually transforming the Delta's coastal transport network from a "C" into an "O."

The Zhoudai Bridge is the "final piece of the puzzle" for Zhoushan's Island-Connecting Expressway. Since it opened to traffic in 2021, the network has reached a total length of 86.68 kilometers, linking eight islands and becoming China's longest island-connecting expressway.

The mega island-linking project

Putting this puzzle together at sea is far more than just joining two pieces. Building a bridge here is like assembling a puzzle on a shaking table.

The waters around the Zhoudai Bridge are frequently hit by typhoons and monsoons, with maximum winds reaching Level 14. The site offers only about 200 workable days a year, while seabed mud layers as deep as 20 to 40 meters make construction even more challenging.

To make offshore construction as efficient as possible, the project adopted a modular construction approach, with major components prefabricated in factories, assembled onshore and then lifted into place at sea. This reduced the impact of harsh sea conditions on construction.

But some work, including in-situ casting of pile caps, component installation and pile driving, still had to be carried out at sea. Engineers had to drive steel pipe piles, up to 109 meters long and two meters in diameter, precisely into the seabed amid rolling seas and strong winds.

During construction, eight sets of anchors were used to keep the construction vessel steady, while a high-precision BDS-GPS dual-mode positioning system kept pile-positioning errors within ±10 centimeters.

But completing the bridge was only the beginning. Streamlined steel box girders, longitudinal dampers and sacrificial anodes help the structure withstand strong winds, earthquakes and seawater corrosion over the long term.

Today, Zhoushan supplies energy and petrochemical raw materials to manufacturing clusters in Shanghai, Ningbo and Hangzhou, while its port network connects the region to domestic and global markets. Improved transport infrastructure allows these different parts of the regional economy to work more closely together.

Transport connectivity and industrial coordination

The Zhoudai Bridge is just one piece of the Yangtze River Delta's broader transport integration.

In recent years, the region has accelerated the development of cross-provincial railways, highways and waterways. In 2026, Shanghai, Jiangsu, Zhejiang and Anhui agreed to advance 44 major interprovincial transport projects.

The region's expressway network now spans nearly 20,000 kilometers, while all 17 of its first batch of cross-provincial "dead-end roads" have been connected, breaking down long-standing transport barriers. For many residents, commuting across provincial borders is increasingly becoming as easy as traveling within the same city.

From linking islands to connecting cities, the Yangtze River Delta is weaving once-separated areas into a more efficient network, allowing people, goods and industries to move more freely.

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Architecture Intelligence: China's ambitious island-linking mega project