Longest Hong Kong rail line put into service, attracting hundred enthusiasts ( 1 Rail enthusiasts wait at the turnstiles to take the first train on the Tuen Ma line in Hong Kong at around 5 a.m. on June 27, 2021. (Photo/ Li Zhihua) The 56 km long Tuen Ma line (TML), the longest railway line in the city, officially set off at 5:50 a.m. on Sunday. The full TML links the West Rail Line and Tuen Ma line phrase -1, serving 27 stations on the journey, including two newly opened stations: Sung Wong Toi Station and To Kwa Wan Station. The commencement of the new line brings passengers a more convenient and efficient commuting experience.