The tunnel is built under the Taihu Lake in Wuxi, East China's Jiangsu province. [Photo provided to chinadaily.com.cn]

Taihu Tunnel, built under the Taihu Lake in Wuxi, East China's Jiangsu province, opened to traffic in the afternoon of Dec 30.

Known as the longest passageway under a lake ever built in China, the 10.79-kilometer tunnel is a two-way, six-lane highway with a designed speed for motor vehicles of up to 100 km per hour. The mega road infrastructure project cost around 5 billion yuan ($784.72 million) and took four years to build.

The tunnel will cut travel time between Mashan and Nanquan - lakeside subdistricts of the city of Wuxi in southern Jiangsu province - by half compared with the current commute, and make it more convenient to travel from the urban area of Wuxi to Yixing, a county-level city administered by Wuxi.

LED variable landscape belts arranged atop the tunnel emulate a starry sky. [Photo provided to chinadaily.com.cn]

Three LED variable landscape belts have been alternately arranged atop the entire tunnel to emulate a starry sky and reduce fatigue among drivers.

The tunnel is considered the most critical node project of the Suzhou-Wuxi-Changzhou South Expressway, the second expressway between Shanghai and Nanjing. It was built by CCCC Third Harbor Engineering and China Tiesiju Civil Engineering Group.

The Changzhou-Wuxi section of the Suzhou-Wuxi-Changzhou South Expressway starts from the Qianhuang hub in Wujin district, Changzhou, passes through Mashan in Wuxi to the southeast and Meiliang Lake of Taihu Lake, and finally reaches the Nanquan hub to connect with the Around Taihu Expressway. The Changzhou-Wuxi section measures 43.9 km in length, of which 22.43 km lies in Wuxi.

An aerial photo of the Taihu Tunnel. [Photo provided to chinadaily.com.cn]