When service of this line started, the section of the Kwun Tong line from Chater to Argyle (since renamed Central and Mong Kok respectively) was transferred to the Tsuen Wan line. Thus, Waterloo station (since renamed Yau Ma Tei station) became the terminus of the Kwun Tong line, and both Argyle and Prince Edward stations became interchange stations. This change was made because system planners expected the patronage of the Tsuen Wan line to exceed that of the Kwun Tong line. This forecast proved to be accurate, necessitating a bypass from the northwestern New Territories to Hong Kong Island. The Tung Chung line was therefore launched in 1998 with an interchange station at Lai King for that purpose.