and efficiency of Shenzhen's subway construction procedures and calls for reform. Subsequently, the Shenzhen municipal government and various departments signed a liability form, requiring Phase II subway expansion to be completed in time for the Universiade. Shenzhen Metro increased to over a hundred operating metro stations in June 2011, just before the Shenzhen Universiade games. In the span of two weeks, the network expanded from to . This expansion increased rail transit's share of total public transit trips from 6% to 29% in 2014. Phase III (2012–2020) In 2010, the Shenzhen Urban Planning and Land Resources Committee proposed a building program (Phase III) between 2011 and 2020. In 2011 this plan was approved by the NDRC. Phase III formally commenced in May 2011 with an expected cost of 125.6 billion yuan. It will cover Lines 6, 7, 8, 9, and 11 and will extend the length of the Shenzhen Metro to and 10 lines. In June 2011, the Shenzhen Urban Planning and Land Resources Commission started gather public input on Phase III station names. On June 28, 2016, Line 11 opened being the first subway line in Shenzhen with 8 car trains and maximum service speed and the first in China with a First Class service. Lines 7 and 9 followed on October 28, 2016. South extension of Line 5 opened on 28 September 2019 and west extension of Line 9 opened on 8 December 2019. Line 6 and Line 10 opened on 18 August 2020 bringing the length of the Shenzhen Metro to and the fourth longest in China. Second east extension of Line 2, second south extension of Line 3, second north extension of Line 4 and phase 1 of Line 8 opened on 28 October 2020 bringing the length of the Shenzhen Metro to . Phase IV (2017–2025) With the shortening of the Phase III implementation period, a number of lines (Lines 16 and 12) planned in 2007's Phase III moved into the next phase. By 2016, it was determined that Phase IV will have an implementation period between 2017 and 2022 and consist of of new subway. Lines 13 and 14 which originally had a long term 2030 completion deadline were moved into Phase IV expansion. In addition, a branch line of Line 6 will connect with the neighboring Dongguan Rail Transit system. Lines 12, 13, 14, and 16 and branch of Line 6 was approved