Taipei: After its planned inauguration in May, the Danjiang Bridge will connect Tamsui and Bali districts in New Taipei at the mouth of the Tamsui River across a nearly 1-kilometer span.
According to Focus Taiwan, the world’s longest single-mast asymmetric cable-stayed bridge has been described by veteran engineers as “a mission impossible” because it demands a careful balance between aesthetics and engineering.
As one of the final works of the late Pritzker Architecture Prize winner Zaha Hadid, the Danjiang Bridge embodies her wish for a design that was “as simple and as elegant as possible,” Huang Shao-wei, an associate director at Zaha Hadid Architects (ZHA), told CNA while recalling the design principles set for the bridge by the “Queen of the Curve.” Huang, a Taiwanese architect who played a key role in ZHA’s winning entry in the 2015 international design competition for the bridge, said the design drew inspiration from the renowned Taiwanese dance troupe Cloud Gate Theater, based a few hundred meters away in Tamsui.
A conventional two-tower suspension bridge would have left one of the towers blocking the path of the setting sun, Huang said, noting that the team eventually decided to design a cable-stayed bridge and remove one of the towers. The single mast, he said, is positioned at a carefully calculated spot closer to the Tamsui side to ensure it does not block the sunset when viewed from major sightseeing spots in Bali and Tamsui. Ultimately, ZHA’s proposal stood out among five other entries, all of which opted for twin-tower bridge designs.
The bridge’s unconventional design, involving numerous custom components, along with its exposed location at a river mouth, posed serious construction challenges and deterred many builders, leading to seven failed tenders between 2017 and 2018. However, Liu Yung-ching, the firm’s deputy general manager, said he was initially opposed to taking on what he described as “a mission impossible.” Liu’s team later drove an additional ring of steel sheet piles around the cofferdam to stop leaks and installed underwater damping devices beneath the bridge to stabilize the structure against strong winds.
In an effort to reduce the overall weight of the bridge, all the steel box girders that form the deck were designed to be welded rather than bolted. However, high humidity and frequent rain at the river’s estuary often made welding impossible. The proposal to build the bridge was first unveiled in 1998 but was later shelved over environmental concerns. It later received approval from the Executive Yuan in 2014 to proceed following several environmental reviews and design modifications.
Construction of the bridge began in February 2019, and it was initially scheduled for completion in 2024. However, the timeline was pushed back by factors such as the COVID-19 pandemic and labor shortages. Those setbacks also pushed up the total budget, which was revised from the original NT$15.43 billion (US$494.11 million) to NT$23.03 billion. With final road paving and lighting work underway and the bridge set to open to traffic on May 12, the Danjiang Bridge marks the end of years of pressure and perseverance for those involved in its planning and construction. Liu, who once harbored opposition and doubt, now speaks with pride, noting that more than a thousand delegations have visited the site to learn about their experience.