Suzhou Rail Transit, also known as Suzhou Metro, is a rapid transit system serving the city of Suzhou, in Jiangsu Province, China. Line 1 began operation on April 28, 2012. Line 2 opened on December 28, 2013. A further three lines, and an extension of Line 2, were completed between 2016 and 2021, with 3 more lines currently under construction and planned to open by 2024. Upon completion, the system will be about 140 kilometres (87 mi) long and have 109 stations. Line S1 of Suzhou Metro connecting neighboring Kunshan city and beyond to the Shanghai Metro is also currently under construction.