Guangdong Transportation: Why is the Shiziyang Passage connecting Guangzhou and Dongguan designed with double layers and sixteen lanes?

Guangdong Transportation: Why is the Shiziyang Passage connecting Guangzhou and Dongguan designed with double layers and sixteen lanes?

The the Pearl River is the mother river of Guangdong. Although it provides a continuous source of water and river passage, there are many obstacles in road traffic...