Line S3 of the Nanjing Metro (Chinese: 南京地铁S3号线; pinyin: Nánjīng Dìtiě S-Sān Hào Xiàn), is a north-south suburban rapid transit line serving part of the southern and southwestern suburbs of Nanjing, running from Nanjing South Railway Station and Gaojiachong. It is the first line of the Nanjing Metro with passing tracks at select stations, allowing from distinct express local services. The first phase of the project is 36.22 km (22.51 mi) long with 19 stations, including 10 underground stations, 8 elevated stations and 1 ground station.^[3] The line crosses the Yangtze River using the Dashengguan Yangtze River Bridge. In 2012, the first phase of the project was approved by the NDRC for construction with the first section started construction on 27 December 2012.^[4][5] On August 13, 2017, the first phase of Line S3 started to be unmanned testing.^[6] The first phase of the line was completed by the end of 2017 and started trial operation on 6 December 2017.^[7]