Shenzhen-Zhongshan Link opens to traffic with 10 world records

China opened the Shenzhen-Zhongshan Link in Guangdong Province, south China, on Sunday, with trial operations scheduled to commence at 3 p.m.

The 24-kilometer passage starts at the Shenzhen airport interchange and connects with Ma'anshan Island in Zhongshan across the Pearl River. It cuts travel between Zhongshan and Shenzhen from two hours to approximately 30 minutes.

The megaproject consists of one underwater tunnel, two bridges and two artificial islands, making it one of the most difficult cross-sea cluster projects in the world. It also holds 10 world records.

As a core transportation project in the Guangdong-Hong Kong-Macao Greater Bay Area, the new link spans about 24 kilometers and has been labeled the "transportation backbone" of the area, shouldering the vital task of seamlessly connecting the urban centers on either side of the Pearl River Estuary.

The link is a key component of the national expressway network G2518, located approximately 30 kilometers north of the Humen Bridge and 31 kilometers south of the Hong Kong-Zhuhai-Macao Bridge. It connects these vital transportation arteries.

The link, along with existing structures like the Hong Kong-Zhuhai-Macao Bridge, will form a network of cross-sea and cross-river passages in the Greater Bay Area, boosting connectivity of the city cluster, said Deng Xiaohua, head of Guangdong Provincial Communications Group.

World records

With a span of 1,666 meters, the Shenzhen-Zhongshan Bridge boasts the world's largest span for a fully offshore steel box girder suspension bridge, the world's highest bridge deck, at 91 meters, and the highest navigation clearance for a sea bridge.

The bridge is the world's largest offshore suspension bridge anchor, with a single anchor's concrete volume measuring approximately 344,000 cubic meters. It boasts the world's highest wind resistance test speed for a suspension bridge, with a maximum flutter test wind speed of 83.7 meters per second. The mega construction also has the world's largest steel bridge deck with hot-mix epoxy asphalt paving, covering an area of 378,800 square meters.

The link's 6.8-kilometer-long undersea tunnel has a central pipe gallery that integrates facilities for power and water supply, drainage, firefighting, communication and intelligent control and serves as an emergency exit.

It is the world's longest two-way, eight-lane immersed tube tunnel, spanning 5,035 meters and consisting of 32 tube sections and one final joint. It is also the world's widest underwater steel shell-concrete immersed tube tunnel, with a standard tube section length of 165 meters, a width of 46 meters – 55.6 meters at its widest – and a height of 10.6 meters.

In addition, the tunnel boasts the world's largest single-volume cast for a steel-shell immersed tube using self-compacting concrete as single tube section concrete volume reaching 29,000 cubic meters, totaling 910,000 cubic meters. It is the world's first underwater expressway interchange and airport interchange, and with a width of three meters, the tunnel is the world's widest repeatedly foldable M-shaped water stop used in the final joint of an immersed tube tunnel.

Smart construction

The Shenzhen-Zhongshan tunnel is the world's longest and widest underwater steel-shell concrete tunnel and is equipped with numerous intelligent devices to ensure its safe and stable operation, including 14 robots, dual-wavelength flame detectors and Beidou satellite navigation signal simulators.

The 5-kilometer-long central pipe gallery is laid with hundreds of cables and pipes of various kinds, with over 10,000 sets of equipment installed. The robots regularly patrol prescribed routes along the emergency exit and cable channel to monitor equipment operation and the environment in the pipe gallery.

In the event of a car accident, they can simultaneously direct traffic with built-in loudspeakers, film the scene and transmit the image to the remote control center in real time.

"We are the first to invent a horizontal smoke exhaust pipe system at the top of the immersed tube undersea tunnel, which improves the smoke exhaust efficiency by 42 percent,"  Ma Ershun, deputy director of the link's management center, told China Media Group. "We have also established a new firefighting and smoke exhaust technology system for ultra-wide and interchangeable undersea tunnels, effectively ensuring safe fire evacuations."

Flanked with lights, the tunnel can change color based on temperature and traffic conditions. In emergencies, the light strips turn red. Meanwhile, the progression from yellow to green, from near to far, guides evacuation. The tunnel is also equipped with intelligent lighting control devices that automatically adjust light brightness to levels that are safe and comfortable, ensuring a pleasant journey for all.