the original West Rail Line. Since its opening as part of the KCR system, the interchange station at Tai Wai has not had ticket gates between the Ma On Shan Rail and East Rail platforms, unlike at the former KCR system's interchanges with the MTR system; a trip from either line to the other counted as one ride. There was no direct connection between these two lines and the West Rail while they were part of the KCR network. Rolling stock For much of its existence, the Ma On Shan line was, in the Hong Kong context, classified as a "medium-capacity system"; however, it is capable of passenger volumes up to 32,000 passengers per hour per direction (PPHPD), which is comparable to the passenger capacity of a full rapid transit or "metro" system. Furthermore, the line has been upgraded to the standard of a full-capacity system in anticipation of the Sha Tin to Central Link, which will extend it to the heart of Kowloon and result in a merger with the full-capacity West Rail line. KCRC initially ordered 18 sets of 4-car SP1950 trains, built by Kinki Sharyo, running on the Ma On Shan line; they have all since been converted to eight cars. The train is the same model as the SP1900 sets used on the East Rail and West Rail lines, which runs on those lines with twelve-car and eight-car configurations respectively (previously seven cars on the latter, though all has been converted to eight cars and used on the entire line following its completion). They were the only trains in use until March 2017, when newly built eight-car Tuen Ma line trains, manufactured by CRRC Changchun Railway Vehicles, entered service on the Ma On Shan line. Both of these models have a maximum running speed of , but only reach a maximum service speed of on the long section between Kam Sheung Road and Tsuen Wan West stations. Unlike the trains on the East Rail line, there are no first-class compartments. All trains were serviced at Tai Wai depot and are equipped with the SelTrac IS moving-block signalling system for train protection, with provision for upgrading to the radio-based SelTrac CBTC at a later stage to increase capacity. The first two converted 8-car SP1900 trains were introduced to the Ma On Shan line on 15 January 2017. During the transition period with both 4-car and 8-car trains