Tuen Ma line

{{Infobox rail line | name = Tuen Ma line
屯馬綫 | color = 923011 | status = Operational | image = Tuen Ma Line C-Train 202103.jpg | image_width = 325px | image_alt = | logo = | logo_width = | caption = A CRRC Changchun EMU train approaching Hin Keng station | type = Rapid transit | system = MTR | mapcolor =      Brown (#923011) | owner = Kowloon-Canton Railway Corporation | operator = MTR Corporation | locale = Districts: Tuen Mun District, Yuen Long District, Tsuen Wan District, Sham Shui Po District, Yau Tsim Mong District, Kowloon City District, Wong Tai Sin District, Sha Tin District | start = Tuen Mun | end = Wu Kai Sha | stations = 30

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| speed =

| ridership2 = 595,700 weekday average
(Sept to Oct 2014, combined from former Ma On Shan and West rail line ridership)^[2]

| planopen =

| open =

| close = | depot = Tai Wai, Pat Heung, Hung Hom sidings | stock = SP1900 EMU (IKK-train)
Tuen Ma Line C-train | linelength = Error in convert: Value "58.8km" must be a number (help)

The Tuen Ma line (Chinese: 屯馬綫) is a rapid transit line that forms part of the Mass Transit Railway (MTR) system in Hong Kong. Coloured brown on the map, the Tuen Ma line is 56.2 kilometres (34.9 mi) in length, making it the longest line of the MTR network. It has a total of 27 stations, more than any other in the MTR system.^[4]

The Tuen Ma line is a merger of the two former MTR lines, the West Rail line and the Ma On Shan line, via a new stretch of mostly-underground railway known as the "Tai Wai to Hung Hom section" (大圍至紅磡段) of the Sha Tin to Central Link project, consisting of 11 kilometres (6.8 mi) of track and six new intermediate stations. The Tai Wai to Kai Tak section (大圍至啟德段) opened on 14 February 2020, while the Kai Tak to Hung Hom section opened on 27 June 2021, thereby completing the line.^[5]

During the planning and construction phase, this line was referred to as the "East West Corridor" (東西走廊). On 25 May 2018, the finalised name "Tuen Ma line" was confirmed by the MTR Corporation, reflecting the termini of the full line, namely Tuen Mun and Ma On Shan. The full journey time is about 73 minutes.^[6]