China opened its longest underwater highway tunnel for the public on Dec 30, 2021, after four years of construction, which started in January 2018.

The Taihu Tunnel stretches under Lake Taihu (the third-largest freshwater lake of China) in Jiangsu province, about 50 km east of Shanghai.

The 10.79 km and 17.45 meters wide tunnel with six lanes was built at a whopping cost of 9.9 billion yuan (about $1.56 billion). Although China has over 100 underwater tunnels, this will be the country’s longest and widest one.

The Taihu Tunnel is part of the 43.9-kilometer Changzhou-Wuxi Highway, which connects the expressways of Suzhou, Wuxi and Changzhou. The tunnel provides an alternate expressway for the travelers commuting between Shanghai and Nanjing, Jiangsu’s capital, thus reducing vehicular traffic in the cities next to Lake Taihu.



The two-way tunnel was built using more than two million cubic meters of concrete. The construction team is believed to have used automatic steel processing equipment and intelligence systems to ensure zero discharge of sewage and dust.

With growing population and urbanization, underwater tunnels are projected as the perfect solution to ease traffic congestion. Among the underwater tunnels worldwide, Channel Tunnel is considered to be the longest. The channel tunnel has the longest underwater section of 37.9 km and connects the U.K. with France.