sci tech | historygg on Instagram: "China has completed the Shenzhen Zhongshan link, a 28 kilometer corridor crossing the pearl river estuary between Shenzhen and Zhongshan. The project combines long span bridges, artificial islands, and a 6.8 kilometer immersed tube tunnel beneath open sea waters. The eight lane tunnel ranks among the widest ever built and reduces travel time from nearly 2 hours to about 20 to 30 minutes. Engineers assembled prefabricated tunnel sections, lowered them with high