every 6 minutes during off-peak hours. Stations from Futian Checkpoint to Shangmeilin Station are underground. The line has been operated by MTR Corporation (Shenzhen), a subsidiary of MTR Corporation, since 1 July 2010. Line 4's color is red. 28 December 2004: Fumin – Children's Palace 28 June 2007: Futian Checkpoint – Fumin 16 June 2011: Children's Palace – Qinghu 28 October 2020: Qinghu – Niuhu Line 5 Line 5, formerly known as Huanzhong line runs from Chiwan in the west to Huangbeiling in the east. Construction began in May 2009 and the line opened on 22 June 2011. Line 5 required a total investment of 20.6 billion RMB. The line is operated by SZMC (Shenzhen Metro Group). Line 5's color is purple. 22 June 2011: Qianhaiwan – Huangbeiling 28 September 2019: Qianhaiwan – Chiwan Line 6 Line 6, formerly known as Guangming line runs from Songgang in the north to Science Museum in the south, with a length of and a total of 27 stations. Construction began in August 2015 and the line opened on 18 August 2020. The line is operated by SZMC (Shenzhen Metro Group). Line 6's color is mint green. 18 August 2020: Science Museum – Songgang Line 6 Branch Line 6 Branch, also known as Branch Line 6, runs from Guangming to SIAT in the north. The line opened on 28 November 2022. Line 6 Branch's color is teal. 28 November 2022: Guangming – SIAT Line 7 Line 7, formerly known as Xili line of the Shenzhen Metro opened on 28 October 2016, with a length of and a total of 27 stations. It connects the Xili Lake to Tai'an. The line travels East–West across Shenzhen in a "V" shape. The line is operated by SZMC (Shenzhen Metro Group). Line 7's color is navy blue. 28 October 2016: Xili Lake – Tai'an Line 8 Line 8, formerly known as Yantian line of the Shenzhen Metro opened on 28 October 2020, with a length of and a total of 7 stations. It connects the eastern suburbs of Liantang to Yantian Road. However, this line serves as the extension of Line 2 in actual operation. The line is operated by SZMC (Shenzhen Metro Group). Line 8's color is orange, the same as Line 2. 28 October 2020: Liantang – Yantian Road Line 9 Line 9, formerly known as Meilin line or Neihuan line of the Shenzhen Metro opened