Shenzhen–Zhongshan Link: China’s 24-Kilometre Sea Superstructure

Driving above the sea, suddenly disappearing into a tunnel, then arriving on an artificial island at a technology museum – this is everyday life in southern China.

A new motorway link between the megacities of Shenzhen and Zhongshan has recently opened, and it sounds more like science fiction than a conventional long-distance road. Across 24 kilometres, China has combined record-breaking bridge construction, a huge underwater tunnel and two artificial islands – including an exhibition centre dedicated to high-tech engineering.

A new bottleneck in China’s booming region

The bay area encompassing Guangdong, Hong Kong and Macao is among the world’s most important economic regions. Industry, logistics and research all depend on fast transport links here. Until recently, drivers travelling from Shenzhen to Zhongshan needed almost two hours, often using congested routes and ferries.

The new connection along the G2518 route cuts that journey to roughly 30 minutes. The toll is equivalent to around €10. For commuters, freight operators and delivery services, this represents a dramatic saving in time – and therefore money.

The route links two megacities in half an hour, where people previously lost half a working day in traffic jams.

Superstructure of steel, concrete and artificial islands

From an engineering perspective, the route brings together several major schemes that would ordinarily each make headlines in their own right. In this case, they have been integrated into one transport project.

• Total length: 24 kilometres above and beneath the sea
• Components: two enormous bridges, an underwater tunnel and two artificial islands
• Journey time between Shenzhen and Zhongshan: around 30 minutes
• Average daily traffic: approximately 86,000 vehicles
• Peak figures: more than 181,000 vehicles per day on travel days

One bridge section is especially spectacular: an exceptionally long suspension-bridge span with steel pylons that holds several world records. To support it, engineers poured the largest concrete anchorage foundation ever built – around 344,000 cubic metres. Structures of this scale are required to protect the crossing from typhoons, waves and extreme loads.

The wind test was correspondingly severe: the system withstood gusts of almost 84 metres per second. These are wind speeds at which conventional structures would already suffer major damage.

The underwater tunnel: eight lanes in an XXL tube

The tunnel beneath the bay is no less striking. Running underground for almost seven kilometres, it is regarded as the world’s widest immersed tunnel built using a steel-and-concrete design.

Measuring 46 metres across, the tunnel system has room for up to eight traffic lanes. Several lanes can therefore operate in each direction at the same time without capacity being quickly exhausted. To motorists, it resembles a wide, brightly lit tube system – yet extraordinarily complex technology sits behind the scenes.

Robots as tunnel police

To keep traffic safe in this sensitive section, a digital network of sensors and machines monitors the entire tunnel. According to project information, the operators use 14 specialised robots that patrol inside the tunnel and continually assess data.

The machines can immediately report unusual situations, such as broken-down vehicles, obstacles or smoke. In an emergency, they help to coordinate an evacuation before emergency services arrive on site. Systems of this kind considerably reduce response times following accidents.

The smoke extraction system operates around 42 percent more efficiently than conventional installations and is intended to save valuable minutes in the event of a fire.

Every minute matters in long tunnels. Modern smoke extraction, ventilation and emergency exits help prevent people from panicking or becoming trapped in smoke. China is using the project to trial new standards that could later be deployed elsewhere.

A traffic giant with its own tourist attraction

Since opening, the route has demonstrated just how eagerly the region had awaited this shortcut. On average, around 86,000 cars use the new link every day. During public holidays and major travel periods, those numbers rise sharply: more than 181,000 journeys have already been recorded within 24 hours.

An express bus network that covers the route quickly, offering an alternative to private cars, is particularly popular. Nearly three million passengers have already used this option. The effect is clear: hotels, restaurants and visitor attractions across the region report substantial increases, while tourism activity rose by more than 100 percent during China’s National Day holiday.

An island shaped like a mythical creature

One unusual feature sits above the route itself. The western of the two artificial islands serves not only as a technical hub but also as a cultural stop. It is home to a new science museum with around 2,200 square metres of exhibition space.

The museum focuses chiefly on marine engineering, high technology and climate risks affecting coastlines. Visitors learn how underwater tunnels are constructed, what forces pull at bridges over the sea, and how computing technology helps keep such structures safe over the long term.

The island’s shape has also been carefully considered. Seen from the air, it resembles the “Kunpeng”, a legendary figure in Chinese mythology that can transform from a giant fish into an immense bird. The symbolism is clear: what appears to be an insurmountable stretch of sea suddenly becomes an aerial leap from one city to another.

What the project means for China – and the rest of the world

For China, the new route is more than a shortcut. It illustrates how strongly the government is seeking to connect its coastal metropolises more closely. Schemes like this support entire industrial clusters: semiconductor plants in Shenzhen, factories around Zhongshan, logistics hubs and ports can work together more effectively.

At the same time, the project sends a message to other countries. Anyone planning to cross major straits, fjords or long bays in the future will look closely at hybrid solutions of this kind: combinations of bridges, immersed tunnels and artificial islands adapted to the shape of the individual coastline.

Opportunities, risks and unresolved questions

Mega-projects of this kind bring major opportunities: less congestion, shorter supply chains, and new jobs in construction, maintenance and tourism. Commuters gain time in their day, while companies can plan more reliably. The museum element also gives the scheme a more welcoming character, attracting school groups and technology enthusiasts.

At the same time, questions remain over environmental consequences. Artificial islands alter currents, marine habitats and bird migration routes. Building tunnels and bridges in open water places pressure on ecosystems, particularly during construction. Supporters argue that modern methods reduce these risks; critics call for long-term monitoring and stricter standards.

A further issue is dependence on digital control systems. Robots, sensors and automated safety technology make the facility efficient, but they also create new points of vulnerability. Cyber-attacks or software faults could have greater consequences in an emergency than conventional technical failures. Operators are therefore investing heavily in redundant systems and emergency plans that can function without high-tech systems if necessary.

For other countries, the Shenzhen–Zhongshan link provides a real-world test bed. Engineering firms and transport planners can examine how the hybrid combination of bridge, tunnel and islands performs in everyday use: how durable are the materials in salt water? How do traffic flows behave in this arrangement? And how well do motorists cope with the rapid sequence of bridge, tunnel and island?

One thing is certain: the new superstructure off the Guangdong coast shows how far highly complex infrastructure construction can already go – and how close science-fiction scenarios have become to the daily commute.