Major tunnel in Jiangsu opens to traffic

The country's longest underwater tunnel which runs for 10.79 kilometers has recently opened to traffic in southern Jiangsu province as part of the Suzhou-Wuxi-Changzhou South Expressway, linking some of the nation's most prosperous city clusters.

The project, acting as the second Shanghai-Nanjing Expressway, traverses Taihu Lake from underneath and has a total investment of 15.91 billion yuan ($2.49 billion).Input for the Wuxi-Changzhou section was 10.37 billion yuan.

The transport artery can lift the capabilities of Shanghai-Nanjing Expressway by linking with the cities of Suzhou, Wuxi and Changzhou and offering a new engine to boost the progress of the Yangtze River Delta region, said Song Heng, a publicity official with State-owned China Tiesiju Civil Engineering Group (CTCE), a builder of the tunnel.

It is incredible for most people to think of the expressway crossing Taihu Lake from underneath, he said, adding the length and width of the tunnel exceeds the underwater tunnel of the Hong Kong-Zhuhai-Macao Bridge, becoming an ultra-wide and ultra-long underwater tunnel in China.

He said using a weir-building method for the massive project and controlling the construction period within three years put a mountainous task before CTCE builders. This meant cutting open the "belly" of the lake with a large-section structure to prevent any water leakage and conducting ant-like transport of lake earth and silt to exterior regions in large quantities.

They also needed to manage the unified sedimentation of pouring bulk concrete, flood control during the main wet season and protecting the water environment, Song said, noting all were accomplished under the prerequisite of creating a national model.

"The main features of our success include our technical prowess which safeguarded this ultra-long and ultra-wide underwater tunnel in China. It traversed Taihu Lake with one tunnel almost 11 km long. We have to consider green construction aimed at water body protection, and easier travel for nearby residents upon operation," Song said.

Taihu Lake－China's third biggest freshwater lake－is located in the Yangtze River Delta. It spans Jiangsu and Zhejiang provinces, and is surrounded by the cities of Wuxi, Huzhou, Yixing and Suzhou. It covers an area of 2,427.8 square kilometers, and has a coastline of 393.2 km.

The No 3 section of the tunnel built by CTCE enters the lake from Wuxi's Binhu district and has a total length of 5.73 km. CTCE builders needed to dig 5.53 million sq m of earth, handle backfilling earthwork of 3.36 million sq m, pour 1.22 million sq m of concrete and use 160,000 metric tons of rebar and 620,000 meters of Larsen SP-IVw steel sheet piles.

"Without our technical innovations, this large-scale project would be a mere fantasy," said Fei Xiaochun, deputy general manager of CTCE Second Engineering Co Ltd and the project's manager and Party secretary.

When they finished building the tunnel, they garnered 10 invention patents, including one from Germany, Fei said.

In January 2018, Fei's colleagues rushed to the worksite to take up the job, and decided to create a "remarkable project" by adhering to a "green" construction concept throughout the entire process, minimizing its impact on the environment.

"Taihu is rich in tourism resources. As the project passes many environmentally sensitive zones, requirements on soil and water conservation, noise control, air pollution and environmental protection－especially the prevention of cyanobacteria in Taihu Lake－are extremely strict," said Cai Chaoyang, Fei's colleague.

They have been working hard on construction organization, clean energy and protecting the ecology of the waters, and made all these possible by sticking to their mechanization, informatization and greening tool kits, Cai said.

The project management department developed and utilized an information-based "electric wave" to safeguard the process, monitor weather and conduct real-time dynamic management over the whole project, thus improving refinements of site management and raising work efficiency of managerial staff.

As the tunnel opened to traffic on Dec 30, residents in Wuxi no longer need to transit the northern part of the city for external travel. To be more specific, by traveling through the Taihu Tunnel, it takes people about just 10 minutes to drive from the city proper to Mashan.

During the drive, riders can enjoy the scenery along the way. Further west, Yixing Bamboo Forest, Changzhou Dinosaur Park at Playland Valley, Maoshan Mountain in Jurong and other scenic spots are easily accessible.