The government approved construction of the Tsuen Wan line in 1977, then known as the Tsuen Wan Extension, and works commenced in November 1978. The project added a section to the MTR system, from Prince Edward station to Tsuen Wan. The line started service on 10 May 1982 with a total cost of construction (not adjusted for inflation) of HK$4.1 billion (US$526 million). The plan was modified from that in the 1970 report "Hong Kong Mass Transit: Further Studies", with Kwai Chung station, Lap Sap Wan station, and a planned depot at Kwai Chung next to Lap Sap Wan station being replaced by stations at Kwai Hing and Kwai Fong and a depot at Tsuen Wan. Several stations also had names different to that during planning: So Uk station became Cheung Sha Wan, Cheung Sha Wan became Lai Chi Kok, and Lai Chi Kok became Lai Wan (later renamed as Mei Foo).