The Airport Railway was built to connect Kowloon Peninsula and Hong Kong Island (over the Western Immersed Tube) to the airport and the planned new town of northern Lantau. The railway is operated by the MTR Corporation and has two routes: the Airport Express and the Tung Chung line which provides a commuter service linking the new town of Tung Chung to the city. These two lines share the same double-tracks for most of their routes, however, the railway was initially planned to have four tracks along its length. The commuter service offered by the Tung Chung line also provided relief to the overcrowded Tsuen Wan line of the MTR.
