Last weekend, China opened a massive cross-sea tunnel and bridge system, the Shenzhen-Zhongshan Link, in Guangdong Province. This engineering feat spanning 24 kilometers (15 miles) features two bridges, two artificial islands, and even a long underwater tunnel.

The Pearl River estuary, where the Pearl River flows into the South China Sea, is one of the world’s most densely populated areas. It includes Hong Kong, Macau, and nine major cities in Guangdong Province. Overall, a staggering 86 million people live there. However, the region has long faced challenges in transportation due to its wide bodies of water.

The newly opened Shenzhen-Zhongshan Link addresses this issue by connecting the two cities it is named after. This link includes an underwater tunnel between two artificial islands and bridges connecting the islands to the cities. The infrastructure boasts eight lanes, allowing speeds of up to 100 km/h (62 mph).

A new way to travel

“Its opening will reshape the road network layout of the Pearl River Estuary, significantly impacting the economic and social development of the GBA,” Lin Feiming, head of the Guangdong provincial department of transport, told state-sponsored Chinese outlet Xinhua.

The mega-crossing will reduce travel time from two hours to just 30 minutes — but not until the hype dies down. During the opening day, too many vehicles showed up, curious to see what the new bridges and tunnels were like after seven long years of construction work. Their curiosity rapidly deteriorated into aggravation as they got trapped in a huge traffic jam.

“On the first day of such a major infrastructure opening, such chaotic management is hard to accept. I don’t see any tunnel staff and traffic police around to maintain order,” said Chan Kam-wai, 76, a retiree taking the bus trip with eight family members.

The 6.8-km-long (4.2-mile) underwater tunnel section — the most difficult and expensive part of this massive engineering project — features cutting-edge safety systems. These include advanced firefighting and smoke exhaust systems, and a team of 14 robots that patrol the tunnel. These robots monitor pipes and cables and can even detect and respond to car accidents. Additionally, a color-coded light system along the tunnel walls can indicate traffic conditions or guide people during emergencies.

Of the two artificial islands in the project, the western one is diamond-shaped, resembling a “kite in the sea”. Meanwhile, the eastern one covers an area equivalent to 48 standard football fields.

More mega-structures

The Shenzhen-Zhongshan Link is the latest in a string of successful Chinese mega infrastructure works. In 2018, the nation opened a $20-billion 55-km-long (34-mile) bridge connecting Hong Kong to Zhuhai. This is the world’s longest sea-crossing by far, just a few kilometers short of the English Channel at its narrowest point.

Known as the Hong Kong-Zhuhai-Macau Bridge (HZMB), the project was designed to withstand a magnitude 8 earthquake, a super typhoon, and strikes by super-sized cargo vessels. The bridge incorporates 400,000 tons of steel – 4.5 times the amount in San Francisco’s Golden Gate Bridge. Like the Shenzhen-Zhongshan Link, the HZMB also features a 6.7-kilometer (4-mile) submerged tunnel.

The new bridge, along with existing structures such as the Hong Kong-Zhuhai-Macau Bridge, now forms an extensive network of sea and river crossings designed to strengthen connectivity between bay area cities.