The Ma On Shan Rail (MOS Rail) is a 11.4km double-tracked electrified domestic passenger railway that provides passenger services operating between Tai Wai & Lee On at Ma On Shan.  The railway serves the increasing population in the Ma On Shan area, a population that is forecast to double in size within the next twenty years.  The stations are located for the most part within easy walking distance of the residential communities which they serve.  The MOS Rail is on viaduct for most of its length, with stations located at Tai Wai, Sha Tin Tau, Sha Kok Street, City One, Shek Mun, Chevalier Garden, Heng On, & Ma On Shan before terminating at Lee On.  Between Shek Mun & Chevalier Garden the railway runs at ground level, along the centre-divide of the Tate’s Cairn Highway.  At Tai Wai station, the MOS Rail has passenger interchanges with the existing East Rail operating between Lo Wu & Hung Hom (Tsim Sha Tsui by 2004).  The depot at Tai Wai accommodates a full range of facilities for the cleaning & maintenance of MOS Rail rolling storck & the maintenance of the railway infrastructure.  MOS Rail is controlled from the existing Train Control Centre at Fo Tan.

The TDD 400 section consists of the new MOS rail station at Tai Wai, modification to the existing KCR East Rail Tai Wai Station, a Public Transport Interchange and enabling work for proposed property development.  The concourse is at grade linking through with the existing concourse with side platform located at an elevated level to provide cross-platform interchange.