Line S9 is a northâÂÂsouth suburban metro line in the Nanjing Metro () system, which opened on December 30, 2017. It connects to Line S1 at and crosses Shijiu Lake on a long bridge between and .
Line S9 also serves as the second stage of the NanjingâÂÂGaochun Intercity Railway, with Line S1 serving as the first stage. In June 2019 a few express trains started operating during rush hour, running non-stop between and .
Line S9 uses car Class B aluminum alloy trains with a maximum service speed of . The train cars are wide with a transverse 2+2 seating layout, with 151 seats and a capacity of 441 people. Unlike most Class B metro trains, each car only has 3 doors per side instead of 4, owing to the line's length and speed.