This study employs annual reports, time-series statistics, and internal training records of the colonial-era Korean Government Railways (KGR) to conduct a quantitative analysis of its labour management practices. It addresses the colonial characteristics associated with Japanese techno-imperialism beyond ethnic discrimination, revealing a dual-pronged labour strategy that adopted a Japanese government employee system to manage middle- and upper-level personnel and directly recruited on-site workers for the lower echelons. This deviates from the low rates of local employment in Western colonies, particularly self-governing British territories or integrated French territories. In contrast, KGR's employment practices demonstrated economic and ethnic inequalities. It predominantly made Koreans on-site labourers, whereas Japanese not only held similar roles, but also occupied upper- and middle-management positions. Worker mobility, particularly among Japanese employees, grew following the outbreak of war between Japan and the USA, leading to the mass external recruitment of Koreans and the expansion of internal education to alleviate labour shortages. Nevertheless, preferential treatment toward Japanese individuals, which had been in relative decline for promotion, wages, and admission rates to training schools, ultimately persisted. Understanding KGR's employment structure shows how colonisation mediated Korea's modernisation and imposed technical limitations on the management of local labour. National technological decolonisation thus required Koreans to further introduce external technologies after the end of Japan's imperial reign.