東區海底隧道
Since opening in 1982, the Tsuen Wan line is the line whose alignment has remained the same for the longest time. For example, the Kwun Tong line's alignment has changed three times since its opening—the taking over of Tsuen Wan line from Mong Kok to Central, the taking over of Eastern Harbour Crossing section by the Tseung Kwan O line, and its extension to Whampoa.