33 Taihu Underwater Tunnel
For creating an underwater path to economic development
The Yangtze River Delta region accounts for about one-fourth of China’s GDP, but mobility challenges were cutting into the region’s growth. “The lengthy commuting time has long dampened people's enthusiasm to seek and keep jobs,” Qian Chunhui of Wuxi Taihu Lake National Tourist Resort told China Daily. And employers in the region “often complain that a main reason for their loss of high-profile talent is the region’s traffic inconvenience.”
To better connect the region—and bolster its economy—the China Tiesiju Civil Engineering Group and Third Harbor Engineering joined forces to build the Taihu Underwater Tunnel. The four-year, CNY9.9 billion project is expected to fuel growth in the region’s health and eldercare service industries as well as boost tourism to the area’s attractions, including the massive Lingshan Grand Buddha statue.
The two-way, six-lane roadway ranks as China’s longest and widest passage under a lake—extending as deep as 20 meters (66 feet) beneath the waterway’s bed. The team used an intelligent, real-time monitoring system as it poured the 2 million cubic meters (70.6 million cubic feet) of concrete. The approach provided powerful lessons learned for leaders at the Jiangsu Provincial Transportation Engineering Group Co. Ltd., which has since promoted the concrete-pouring practices across the province.
Yet the team faced not just engineering challenges, but also environmental ones. The structure runs under Lake Taihu, China’s third-largest freshwater lake, which supplies water to around 30 million people. For decades the lake has suffered severe pollution, and project leaders knew from the start that the initiative couldn’t exacerbate the situation. To minimize dust, noise pollution and fleet emissions, the team used an enclosed concrete mixing plant and relied on eco-friendly electric vehicles. Aboveground, the team avoided dust and noise pollution by operating an enclosed concrete mixing plant and using hydraulic pile hammers that operate at a decibel level estimated to be half that of traditional models.
Open to traffic since January, Taihu Underwater Tunnel serves as a crucial piece of the larger 44-kilometer (27-mile), CNY15.9 billion Suzhou-Wuxi-Changzhou Highway that debuted at the same time. And while increasing efficiency was the name of the game, the team didn’t ignore design aesthetics. When creating the tunnel’s three ventilation areas, for example, it tried to play off the surrounding landscape. The middle vent was made into an islet 150 meters (492 feet) wide, and those on either end were formed into statues: one of a conch, the other of an ancient boat. The team also tricked out the structure’s ceiling with colorful LED lights to prevent driver fatigue.