China has completed the Shenzhen–Zhongshan Link, a massive 28-kilometer transport corridor crossing the Pearl River Estuary. The project combines long-span bridges, artificial islands, and a 6.8-kilometer immersed tunnel beneath the open sea. Its eight-lane tunnel is among the widest of its kind, cutting the journey between Shenzhen and Zhongshan from nearly two hours to roughly 20–30 minutes. Engineers installed massive prefabricated tunnel sections with extreme precision, lowering and sealing