South Island line

A test train approaching Wong Chuk Hang station in December 2015

Project Agreements and Entrustment Agreement for MTR South Island line and the Kwun Tong line extension were signed by the Hong Kong government and MTR Corporation on 18 May 2011.[7] In August 2012, drilling and blasting work began for constructing the Nam Fung Tunnel, between Admiralty and Ocean Park stations.[8] The line was built by a Leighton Asia – John Holland Group joint venture.[9][10]

On 9 December 2013, structural work for Ocean Park station was completed.[11][12] The first 3-car trainset arrived at MTR Siu Ho Wan Depot on 19 February 2014.[13] The project was 78% complete by late September 2014, and Nam Fung Tunnel was broken through on 17 October.[8] In 2015, trial runs began between Wong Chuk Hang and South Horizons stations. 84% of construction work was completed by the end of February 2015. Work in Lei Tung station was prolonged by geological problems, but the MTR claimed it would not postpone the line opening.[14]

Expansion works at Admiralty station in November 2016. Underground are a new concourse, and the platforms of the South Island line and the North South Corridor. Harcourt Garden will be restored as a podium garden after the completion of the work.

The opening of the South Island line was originally planned for 2015. On 21 May 2014, an informant told Apple Daily that the commencement date of the line would be postponed by one and a half years. MTR Corporation asserted it would be opened as expected. Yet, the Transport and Housing Bureau revealed the delay of construction work and demanded MTR to review the commencement. Members of the Legislative Council and District Council criticised MTR for hiding the project's progress from the public and demanded a progress report at the Council's meeting.[15] Eight days later at the South District Council meeting, MTRC announced the delay was caused by the expansion work of Admiralty station. High-density building, underground public facilities and the existing Admiralty station would prolong the work progress, as "safety comes first". However, the claimed 2015 opening date remained unchanged.[16] In November 2014, a revised opening date of December 2016 was announced.[17]

In October 2016, MTRC chairman Frederick Ma warned that the opening of the South Island line could be delayed by three more months.[18] However, on 10 November 2016, he announced the South Island line would open by the end of 2016, saying the engineering team overcame the many challenges in expanding Admiralty Station.[19] Finally, MTRC chief executive Lincoln Leong officially declared the South Island line would begin operation on 28 December 2016.[4]

At Admiralty, a new island platform was built under Harcourt Garden.[22] Transfer passages connect the new station area with the older Tsuen Wan line and Island line platforms, as well as the East Rail line platforms.

At Wong Chuk Hang, the platform structure was planned to be a double island platform with three tracks (like Choi Hung station). South Island line (West) trains would use the centre track while South Island line trains would use those on each side, allowing for convenient cross-platform interchanges. However, according to the final plan, any future South Island line (West) platforms were to be built above the existing platforms.