The Tung Chung Line, unlike most urban MTR lines, is mostly above ground, and unlike other MTR lines, which are approximately 15 km on average length, this line has a total length of just over 30 km. At the same time, most of the line runs along the Airport Express. The Tung Chung Line runs from the east to west. The line is underground from Hong Kong station and crosses the harbour to Kowloon Station. The line then emerges to the surface outside Olympian City 2, to reach Olympic Station at the surface.
After Olympic station, the line runs at ground level beneath the West Kowloon Expressway, stopping at Nam Cheong Station. Then, the line rises above the ground onto a viaduct, which is also built under the West Kowloon Expressway. The viaduct leads into a tunnel in the hills near Lai King. It emerges shortly at Lai King Station to provide cross platform interchange with the Tsuen Wan Line.
The line remains on viaduct past Lai King station, and crosses Rambler Channel on the Tsing Lai Bridge to Tsing Yi Island, where it enters Tsing Yi Station. Having passed Tsing Yi station, the line enters another tunnel through the hills of Tsing Yi. It travels on the Tsing Ma Bridge and the Kap Shui Mun Bridge, crossing Ma Wan island but no stops within the island.
Eventually, the line leaves the tunnel and travels on the surface along the North Lantau Expressway. It stops at Sunny Bay Station on the way. The line then shares tracks with the Airport Express before splitting from it just before it reaches Tung Chung New Town. Having re-entered the tunnel, the line terminates at Tung Chung Station, located underground.
With a displacement of over 10 km between Sunny Bay and Tung Chung, and no intermediate stations within this section of the track (other than the Siu Ho Wan depot), it takes about 8 minutes to travel between these stations. There are currently no intermediate stations within this section of the track because there are no suitable sites or facilities nearby.