China Built an 8-Lane Highway Under the Sea, Here’s How

China built a highway beneath the sea. The Shenzhen–Zhongshan Link is a 24-kilometre megaproject combining two bridges, two artificial islands and a 6.8-kilometre underwater tunnel beneath the Pearl River Estuary. Instead of drilling the tunnel traditionally, engineers constructed enormous steel-shell concrete sections on land, floated them into position and lowered them into a prepared trench on the seabed. The finished eight-lane route reportedly cost ¥44.69 billion and took seven years to complete. Since opening in June 2024, it has reduced travel between Shenzhen and Zhongshan from approximately two hours to around 30 minutes. In this documentary, we explore how China sank a highway beneath the sea, why engineers chose a tunnel instead of one continuous bridge and whether megaprojects like this can justify their enormous cost. Would you feel comfortable driving beneath the seabed? Subscribe to Scale & Steel for documentaries about the machines, megaprojects and industrial systems reshaping the modern world. #China #Engineering #Megaprojects #UnderwaterTunnel #infrastructure