Ma On Shan line

The Ma On Shan line (Chinese: 馬鞍山綫) (formerly known as Ma On Shan Rail from 21 December 2004 to 2 December 2007 and Tuen Ma line Phase 1 from 14 February 2020 onwards) was a commuter rail / rapid transit line that formed part of the Mass Transit Railway (MTR) system in Hong Kong. Coloured brown on the MTR map, the line acted as a branch of the East Rail line that connects the new towns of Sha Tin and Ma On Shan in the northeastern New Territories.

The railway was one of three built by the Kowloon-Canton Railway Corporation (KCRC), which named it as Ma On Shan Rail (Chinese: 馬鞍山鐵路, abbreviated as 馬鐵). Since KCRC's merger of operations with the MTR Corporation on 2 December 2007, the line has been operated as part of the MTR network. Along with the West Rail line, the line was integrated into Tuen Ma line Phase 1 on 14 February 2020 following the partial opening of the Sha Tin to Central Link.

This is the only line without platform screen doors which is opposed to the West Rail line, until the line was extended to Kai Tak station which had platform screen doors.