On August 24, the "Industry Observation · Into the Frontline of Major Projects" column of People's Daily focused on the Shenzhen-Zhongshan Link and reported under the title "Another Mega Project Will Span the Lingdingyang Estuary in the Guangdong-Hong Kong-Macao Greater Bay Area — Construction of the Shenzhen-Zhongshan Link Advances Solidly." The full text follows:

Another Mega Project Will Span the Lingdingyang Estuary in the Guangdong-Hong Kong-Macao Greater Bay Area —

Construction of the Shenzhen-Zhongshan Link Advances Solidly

Standing on Ma'an Island in Zhongshan, Guangdong and gazing into the distance, the Shenzhen-Zhongshan Link under construction winds across the deep blue sea, at times leaping into the air and at times diving beneath the waves, running 24 kilometers to reach Qianhai in Shenzhen. Following the Hong Kong-Zhuhai-Macao Bridge, this mega sea-crossing corridor integrating "tunnel, island, bridge and underwater interchange" will once again set multiple world records.

Viewed from a higher vantage point, the Shenzhen-Zhongshan Link lies 30 kilometers north of the Humen Bridge and 31 kilometers south of the Hong Kong-Zhuhai-Macao Bridge, forming the key "horizontal stroke" of the "A"-shaped main transport framework of the Guangdong-Hong Kong-Macao Greater Bay Area. After it is completed and opened to traffic next year, the drive from Zhongshan to Shenzhen will be shortened from 2 hours to 20 minutes, making it a major transport artery connecting the city clusters on both sides of the Pearl River Estuary. How is this super project built? How are the "world's bests" achieved? A few days ago, the reporter rushed to the construction site to find out.

View of the Lingdingyang Bridge of the Shenzhen-Zhongshan Link.

A Kite at Sea

In just four and a half months,
an artificial island equivalent in size to 19 football fields

was built in the vast open sea

On a summer morning, viewed from above, the sea surface sparkles, and the Shenzhen-Zhongshan Link resembles a giant "kite at sea" poised to spread its wings and fly.

Construction site of the west artificial island of the Shenzhen-Zhongshan Link

The "kite face" of this kite is the west artificial island of the Shenzhen-Zhongshan Link. To ensure that the Lingdingyang waters retain a 300,000-ton-class navigable capacity, the Shenzhen-Zhongshan Link adopted a design of a tunnel in the east and a bridge in the west. "The east side is an undersea tunnel and the west side is a sea-crossing bridge. To join the two, an artificial island must first be built in the sea," said Zhang Changliang, director of the Island and Tunnel Engineering Management Department of the Shenzhen-Zhongshan Link Management Center.
In the vast sea, how was the "first move" made?
"The open sea is more than 10 meters deep, with soft soil layers tens of meters thick — like building an island on 'water tofu.' Traditional rubble caissons tend to slide and are difficult to fix in place," said Zheng Weitao, deputy chief engineer of the Shenzhen-Zhongshan Link project department of CCCC First Harbor Engineering. Drawing fully on the experience of the Hong Kong-Zhuhai-Macao Bridge, the team proposed a brand-new island-enclosure scheme using large deeply inserted steel cylinders: 57 giant steel cylinders, each with a diameter equal to the length of an international standard basketball court and a height of 13 stories, were driven into the seabed, and then sand was filled in to form the island.
However, the sea does not easily submit to human will. After seabed exploration, the problem stood before them. "The seabed structure here not only has thick silt but is also riddled with hard interlayers of varying depths; the geological conditions are harsher than those at the artificial island of the Hong Kong-Zhuhai-Macao Bridge," Zheng Weitao told the reporter. Working on this uneven "water tofu" makes positional deviation very likely.
"Without solving the geological problems, everything is just empty talk." Zheng Weitao pointed to a deep underwater mixing vessel not far away, saying it was the "hero" that cracked the problem. The vessel is like a giant mixer: its three attached drill pipes can penetrate the sand layer, inject slurry and soften the geology, making it easier for the steel cylinders to penetrate the hard sand layer and reach the designed position precisely.
With tests successful and the steel cylinders ready, on May 1, 2017, the curtain officially rose on island construction — a 10,000-ton vessel carrying the first large steel cylinder slowly sailed into the Lingdingyang waters, with hundreds of construction workers lined up at sea to welcome it. The 4,000-ton-class crane vessel "Yihang Jintai" extended its long sling and steadily hoisted the hydraulic vibratory hammer group together with the large steel cylinder, placing it precisely in the water under the guidance of a self-developed positioning system.
At the command "Begin vibratory sinking," the sea surface suddenly came alive. "Buzz, buzz, buzz—" the world's largest twelve-hammer linked hydraulic vibratory hammer group exerted force simultaneously, sounding like a bell and surging like a rainbow. More than three hours later, the steel cylinder weighing over 600 tons was steadily inserted more than 10 meters into the seabed, with a positioning accuracy of 100%.
"Compared with the Hong Kong-Zhuhai-Macao Bridge, the steel cylinders of the Shenzhen-Zhongshan Link are longer in diameter and heavier, and the vibratory sinking operation requires greater power," Zheng Weitao said proudly. The team optimized and upgraded the original eight-hammer linked hammer group to design and manufacture a twelve-hammer linked group, with a maximum driving force of 5,900 tons, leading the industry. In the months after the first steel cylinder was successfully sunk, this technique was "replicated" 57 times. "After Super Typhoon Hato passed, we measured every cylinder and found almost no change in position; both structure and stability withstood the test," Zheng Weitao said.
On September 18, 2017, with the last steel cylinder sunk into place, the outer cofferdam of the west artificial island traced out a "kite at sea" like a string of pearls. In just four and a half months, in the vast open sea dozens of miles offshore, an artificial island the size of 19 football fields was built out of thin air, setting a world record for rapid island creation.

Embroidery on the Seabed

32 immersed tube sections joined end to end and laid on the seabed,
a 6.8-kilometer undersea tunnel "holding hands" beneath the waves

For the "kite at sea" to dance gracefully, it needs a sturdy and durable "tether" — a 6.8-kilometer undersea tunnel.
According to the corridor design, the tunnel section requires 32 immersed tube sections to be placed in deep soft-soil layers more than 30 meters below the sea to achieve two-way, eight-lane undersea traffic. This is also currently the world's longest and widest steel-shell concrete immersed tube tunnel.
Setting aside the intricate internal structure of each immersed tube, just looking at its "physique": each standard section is 165 meters long and weighs about 80,000 tons. Sinking these 32 "big guys" to the seabed, joining them end to end with a perfect fit, and ensuring the entire project is "leak-proof" over its 100-year design life is an unprecedented challenge.
Manufacturing the giant steel-shell immersed tubes was the first hard battle.
Outside the Pearl River Estuary, on Niutou Island in Zhuhai, the world's largest immersed tube prefabrication factory has been built through the construction of the Hong Kong-Zhuhai-Macao Bridge. "According to project requirements, we must produce one immersed tube section per month. That means the longitudinal movement of the steel-shell immersed tube within the factory must be completed within one day. To achieve this, intelligentization is the only way," said Luo Bing, deputy production manager of the Shenzhen-Zhongshan Link project of CCCC Fourth Harbor Engineering.
After more than 80 discussions, over 300 drawings and 23 technical攻关 (key-problem-solving efforts), a complete intelligent manufacturing scheme emerged: 200 self-developed intelligent trolleys move in sync, carrying the steel shell to the casting area within 4 hours. Then intelligent casting robots take over, intelligently calculating the casting speed and controlling the concrete discharge height in real time so that each cell is fully filled, ultimately completing one steel-shell immersed tube section.
Producing the immersed tubes was only the first step. From the immersed tube prefabrication factory to the docking area at the west artificial island is nearly 50 kilometers; how to float the tubes into place became a new test.
The project team first proposed widening the two installation vessels originally used for the Hong Kong-Zhuhai-Macao Bridge immersed tubes to match the width of the Shenzhen-Zhongshan Link tubes. However, since the two vessels cannot self-propel, the widened hulls would need tugs on both sides for towing, and the existing channel width could not accommodate the formation of installation vessels and tugs. Building a new self-propelled semi-submersible vessel would take a long time and involve high operational risks.
What to do? At an expert seminar in 2016, Li Yiyong, then deputy general manager and chief engineer of CCCC First Harbor Engineering, and his team had a flash of inspiration: could the two installation vessels be transformed into a single integrated structure, with main and side thrusters providing towing power?

The integrated vessel carrying a tube section to the tunnel site

A change of thinking opened up a world of possibilities. After more than a year of refinement, construction and commissioning, the world's first integrated immersed tube floating and installation vessel, "Yihang Jin'an 1," turned from concept into reality: 190 meters long, 75 meters wide and nearly 15 meters deep, it can precisely sink and dock immersed tubes 50 meters underwater even when carrying an 80,000-ton tube section.
Next came the most severe test: placing the first immersed tube section at its predetermined position deep in the sea.
At 2 a.m. on June 16, 2020, an 80,000-ton immersed tube section was towed out of the dock at Niutou Island and merged with the 20,000-ton integrated vessel. Accompanied by 8 tugs and maritime vessels, they passed under the Hong Kong-Zhuhai-Macao Bridge, entered the Lingdingyang channel, went through 7 channel transitions, overcame challenges such as grounding in shallow-water channels and heavy back-silting, and finally arrived at the installation point.
After the long journey, the immersed tube began its "deep-sea kiss": operators slowly lowered the tube onto the seabed foundation bed via winches, and excess water was expelled through hydraulic compression, so that the tube and the fixed section "embraced tightly."
From the successful "debut" of the first immersed tube to the successful installation of the last, laying 32 tube sections on the seabed took a full three years.

The last tube section and the final joint being sunk and docked

At noon on June 9 this year, more than 150 technical personnel stood ready in the command hall of the integrated vessel. Viewed through the BeiDou navigation system, the underwater operation was fully visible: the last immersed tube section was steadily placed in the designated position, after which the final joint was slowly pushed out by the jack system, then pressed, aligned and sealed.
"The E23 tube section has completed undocking, floating and installation, and the final joint has been pushed out; the measurement tower and diver inspection show that the accuracy meets requirements!" Ning Jinjin, executive deputy chief engineer of the Shenzhen-Zhongshan Link project department of CCCC First Harbor Engineering, reported excitedly on site.
Nearly 70 hours of tension instantly turned into jubilation. Everyone knew this meant the undersea tunnel of the Shenzhen-Zhongshan Link had been successfully holed through, and the cities of Shenzhen and Zhongshan had "joined hands" beneath the Lingdingyang seabed.
In the early hours of June 11, celebratory fireworks rose over Lingdingyang, soaring into the sky and piercing the night, reddening the smiling faces of onlookers at sea.

Threading a Needle in the Wind

The world's largest sea anchor block holds fast
the world's highest-navigable-clearance sea bridge,

with a main cable of 199 wire strands erected 270 meters above

If the tunnel is a "hidden line" beneath the water, then the bridge is the "flying line" that lifts the "kite at sea" into the sky.
This is by no means a simple line. About 17 kilometers long in total, it starts from the approach bridge on Ma'an Island in Zhongshan, passes through the Zhongshan Bridge and the Lingdingyang Bridge, and finally connects to the west artificial island. With a main span of 1,666 meters, the Lingdingyang Bridge is the world's largest-span fully offshore sea steel box girder suspension bridge, and with its 270-meter main towers it is the world's sea bridge with the highest navigable clearance.
To ensure navigability, the Lingdingyang Bridge has a navigable clearance of 76.5 meters, the highest in the world. To achieve such clearance, two even taller main towers had to be built over Lingdingyang.
"A long-span suspension bridge requires a more solid anchor block as the load-bearing structure." Following the direction of Liao Wenlong's finger — deputy manager of the Shenzhen-Zhongshan Link project department of CCCC Second Harbor Engineering — a huge "counterweight" sits firmly in the sea where the main cable meets the water. "A single anchor block of the Lingdingyang Bridge weighs 170,000 tons, the world's largest sea anchor block. It is like the person at the end of a tug-of-war rope, using body weight to hold the main cable and bear the weight of the entire bridge and vehicles."
With no support in the vast ocean, where to begin? Build an artificial island to convert offshore construction into onshore construction. Next to the artificial island is a living platform half a football field in size; a "town" assembled from 130 containers has become what the workers call "sea-view rooms," where some stayed for more than four years. "The longest time, I didn't leave the island for three months, listening to the waves by day and watching the stars at night," Liao Wenlong recalled clearly the day he left the island — April 28 this year, "the day the bridge was holed through; all the perseverance was worth it."

Construction site of the Lingdingyang Bridge of the Shenzhen-Zhongshan Link

The anchor block is embedded deep in the sea, the main towers stand tall, and two suspended cables tightly connect the two. These cables are the bridge's main cables, the "lifeline" of a suspension bridge.
"To erect a suspension bridge, first walk the catwalk." Zhang Ping, deputy manager of the Shenzhen-Zhongshan Link project department of CCCC Second Harbor Engineering, said that as the aerial construction passage for laying the main cables, the catwalk runs through the entire superstructure construction of the suspension bridge.
Stepping into a five-foot-square elevator built close to the main tower, moving to the construction platform and climbing two more flights of stairs, the reporter reached the tower top 270 meters above the sea — about the height of a 90-story building — and the fully exposed catwalk came into view: two 3-kilometer-long, only 4-meter-wide aerial corridors spanning the channel, with steel wires tied into a mesh floor and waist-high railings on both sides. Summoning courage and taking small steps forward, with white clouds flying overhead and waves churning below, one cannot help but feel weak in the knees.
For more than two months, construction workers shuttled back and forth at such a height of over a hundred meters, "threading the needle" for the bridge — moving 199 wire strands, one by one, with anchor heads attached, from one end to the other and laterally into the anchor, ultimately forming a main cable 1 meter in diameter and strong enough to bear 150,000 tons.
"Every one of us is a 'tightrope walker,' and we walk the world's highest and longest 'tightrope' over the sea." Zhang Ping has been building bridges since 2007, and this is the seventh suspension bridge he has participated in. "To build a world-class bridge with the highest construction standards, no one, no day and no procedure can afford the slightest slack — that is what the Lingdingyang Bridge demands of us bridge builders."
At present, all bridges along the Shenzhen-Zhongshan Link have been holed through, and construction of bridge deck ancillary facilities is in full swing. Heading east along the bridge, follow-up construction of the artificial island and undersea tunnel is in full swing, and a giant "kite at sea" connecting the city clusters on both sides of the Pearl River Estuary has leapt onto the sea surface, becoming a spectacular sight over Lingdingyang.