and the train color is purple, the first of which were delivered in April 2015. The line started operation on January 18, 2017. Line 4's color is purple. Line 7 Line 7 is a northeast–southwest line roughly following the south bank of the Yangtze River. The south section has been under construction since November 2017. The rest of the line started construction in November 2018. The north section opened on 28 December 2022. This line is also the first line of Nanjing Metro to use GoA4 automated trains. Line 7's color is dark green. Line 10 Line 10 is a western extension from Line 1's Olympic Stadium branch line, which broke away from Line 1 and formed part of Line 10 when the new line was completed. Construction started in February 2012, finished in 2014. The line is approximately long with 14 stations, and entered operation on July 1, 2014. Line 10's color is beige. Line S1 Line S1 acts as Nanjing's airport express line, connecting Nanjing South Railway Station to Gaochun District via Nanjing Lukou International Airport. The entire line was planned to be long with 13 stations. The first phase from Nanjing South to Lukou International Airport started construction on December 27, 2011, and finished in 2014. The first phase opened on July 1, 2014, in time for the Nanjing 2014 Summer Youth Olympics. It is long with 8 stations. The second phase extension later became Line S9. Line S1's color is teal. Line S3 Line S3 opened on 6 December 2017. It starts from Nanjing South Railway Station and heads west, crossing the Yangtze River on the cantilever along the edge of Dashengguan Yangzte River bridge together with high-speed rail trains, before terminating at the Gaojiachong station in Qiaolin, southwest of Pukou District. Originally planned as Metro Line 12 or the Ninghe Intercity Rail Line, the route started construction in late 2011. Besides Nanjing South Railway Station in which passengers can transfer to Lines 1, 3, or S1, Youfangqiao station is also a transfer station between Line S3 and Line 2. Phase one is long with 19 stations and connects Nanjing South Railway Station to Jiangbei New Area in Pukou. Phase 2 is now still being planned, which might extends further southwest from Phase 1 to Hexian county in the far future. Line S3's color is magenta. Line S6 Line S6 or the Nanjing-Jurong Intercity Railway is