Xi’an opens second north-south metro line
https://www.metro-report.com/news/metro/single-view/view/xian-opens-second-north-south-metro-line.html
As is often the case with China's metro, so many metro lines open at the same time in December.
This December, new metro lines or extension of existing lines were inaugurated in Beijing, Shanghai, Xian, Chengdu, Chongqing, Guiyang, Guangzhou, Tianjin, Qingtao, and Wuhan.
