Technicians take part in the cold-running test at a section of Shanghai Metro Line 18 in east China's Shanghai, April 26, 2021.  (Xinhua/Fang Zhe) 

With two new metro lines set to go into operation on Dec. 30, the total length of Shanghai's metro network will extend to 831 km, continuing to be the longest in the world, according to Shanghai Metro.

The opening of the two new lines will bring the total number of fully automatic metro lines in Shanghai to five, with an operating length of 167 km, ranking first in the world for the first time, Shanghai Metro said.

The new Line 14 with an operating length of 38 km is the first fully automatic metro line for eight-car trains in Shanghai. With 31 stations, it is expected to serve as a horizontal artery in the metropolis.