Aerial photo taken on Dec. 23, 2020 shows a portal crane assembling track sections at the construction site of Shaoguang Station of the Changsha Subway Line 6 in Changsha, central China's Hunan Province. The construction of the Changsha Subway Line 6 entered the phase of track laying Wednesday. The 48.11-kilometer line with 34 stations will serve as an east-west aorta of urban transportation in Changsha, and is expected to start pilot operation before the end of 2021. (Xinhua/Chen Sihan)