The Tseung Kwan O Line is one of the eleven lines of the MTR system in Hong Kong. It runs from Hong Kong Island to the new town of Tseung Kwan O. The line is indicated with the colour purple. During the morning peak period, the Tseung Kwan O Line needs 15 trains in service to keep 2.7 minute intervals. It currently travels through seven stations in 15 minutes along its route.
This line was planned to serve the new town of Tseung Kwan O (literally, General's Bay) and was first proposed in 1985, construction cost estimated as 3 billions Hong Kong dollar, suggest starting to built in 1992 and planned to be open by the end of 1996, but this plan was cancelled by MTR Corporation in August 1990, then re-proposed in 1993. After being approved by the Hong Kong Executive Council on 20 October 1998, construction commenced on 24 April 1999. The line opened on 18 August 2002, the total cost during construction was 18 billions HKD, and took over the train tracks running through the Eastern Harbour Tunnel from the Kwun Tong Line. Subsequently, the Kwun Tong Line was diverted to Tiu Keng Leng station on the new line.
This line is the first MTR line with no track on viaducts. The portion of the line between Yau Tong and Po Lam has its concourses set on ground level or above, unlike other stations on the MTR network which have concourses underground. Trains at Yau Tong, Po Lam and LOHAS Park are also at ground level, but are completely covered to minimise noise to the surrounding development. The rest of the line has its tracks below ground level.
According to Rail Projects Under Planning 2000 released by Highways Department; in the North Island Line proposal, the Tseung Kwan O line will extend from North Point Station westwards to Tin Hau Station, and connect up with the western portion of the Island Line.