Why is the north extension project of Nanjing Yin Tian Avenue progressing so slowly?

It's hard to build. According to the information of Nanjing local treasure, Yin Tian Avenue built in Nanjing needs to be built across regions, and there will be many obstacles in the middle. Moreover, the bridge itself is multi-lane and needs to meet the driving of many vehicles, which leads to the difficulty of bridge construction and the slow progress of north extension.