Editing MTR (section)

=== Line extensions ===
{{Main|Tsuen Wan line|Island line (MTR){{!}}Island line}}
The government approved construction of the [[Tsuen Wan line]] in 1977, then known as the Tsuen Wan Extension, and works commenced in November 1978. The project added a {{convert|10.5|km|mi|adj=on}} section to the MTR system, from [[Prince Edward station]] to [[Tsuen Wan station|Tsuen Wan]]. The line started service on 17 May 1982 with a total cost of construction (not adjusted for inflation) of HK$4.1&nbsp;billion<ref name="thepast" /> (US$526&nbsp;million). The plan was modified from that in the 1970 report ''Hong Kong Mass Transit: Further Studies'', with [[Kwai Hing station|Kwai Chung]] station, [[Kwai Fong station|Lap Sap Wan]] station, and a planned depot in Kwai Chung next to Lap Sap Wan station being replaced by stations in [[Kwai Hing station|Kwai Hing]] and [[Kwai Fong station|Kwai Fong]] and a depot in Tsuen Wan. Several stations also had names different to that during planning: So Uk station became [[Cheung Sha Wan station|Cheung Sha Wan]], Cheung Sha Wan became [[Lai Chi Kok station|Lai Chi Kok]], and Lai Chi Kok became Lai Wan (later renamed [[Mei Foo station|Mei Foo]]).

When service of this line started, the section of the Kwun Tong line from Chater to Argyle (since renamed Central and Mong Kok respectively) was transferred to the Tsuen Wan line. Thus, Waterloo station (since renamed [[Yau Ma Tei station|Yau Ma Tei]]) became the terminus of the Kwun Tong line, and both Argyle and Prince Edward stations became interchange stations. This change was made because system planners expected the patronage of the Tsuen Wan line to exceed that of the Kwun Tong line. This forecast proved to be accurate, necessitating a bypass from the northwestern New Territories to [[Hong Kong Island]]. The [[Tung Chung line]] was therefore launched in 1998 with an interchange station at [[Lai King station|Lai King]] for that purpose.<ref name="thepast" />

Although land acquisitions were made for a station at Tsuen Wan West (near [[Tsuen King Circuit]]), beyond Tsuen Wan station, as part of the Tsuen Wan branch, the station was never built. This is not to be confused with the modern-day [[Tsuen Wan West station]] on [[Tuen Ma line]], which lies on a newly reclaimed area near the former ferry pier.

Since opening in 1982, the Tsuen Wan line is the line whose alignment has remained the same for the longest time. For example, the Kwun Tong line's alignment has changed three times since its opening—the taking over of Tsuen Wan line from Mong Kok to Central, the taking over of Eastern Harbour Crossing section by the Tseung Kwan O line, and its extension to [[Whampoa station|Whampoa]].

Government approvals were granted for construction of the [[Island line (MTR)|Island line]] in December 1980. Construction commenced in October 1981. On 31 May 1985, the Island line was opened with service between [[Admiralty station (MTR)|Admiralty station]] and [[Chai Wan station]]. Both Admiralty and [[Central station (MTR)|Central]] stations became interchange stations with the Tsuen Wan line. Furthermore, each train was extended to eight cars.<ref name="thepast" /> On 23 May 1986, the Island line was extended to [[Sheung Wan station]]. Construction was delayed for one year, as government offices which were located over the station had to be moved before the construction could start.

In 1984, the government approved the construction of the [[Eastern Harbour Crossing]], a tunnel to be used by cars and MTR trains. The Kwun Tong line was extended across the harbour on 5 August 1989 to [[Quarry Bay station]], which became an interchange station for the Kwun Tong line and the [[Island line (MTR)|Island line]]. An intermediate station, [[Lam Tin station|Lam Tin]], started operations on 1 October 1989.<ref name="thepast" />