In 1974 a 10-year investment programme was started to provide for the complete double-tracking and electrification of the railway from Hung Hom to Lo Wu, requiring the building of a second Beacon Hill Tunnel together with the construction or upgrading of stations and other facilities. This exercise was completed by the early 1980s and on 16 July 1983 the use of diesel-hauled trains ceased for domestic passenger services. Diesel locomotives continued to be used for through-train passenger services, which resumed in 1979 following implementation by Deng Xiao Ping of economic reforms in China, and for freight and track maintenance services.