Route 505 is an MTR Light Rail route linking Sam Shing stop and Siu Hong stop, in the southern and northern parts of Tuen Mun, Hong Kong, respectively. The route is coloured red on the Light Rail system map. The route has three one-way segments: Kei Lun and Siu Hong are on a one-way clockwise loop at the northern end of the line; and in the middle of the route there is a split such that Shan King (North) and Shan King (South) are only served by northbound trains, and Ming Kum only by southbound trains.