The article analyses the socio-economic transformations brought about by capital investments in colonial transport infrastructure in Sekondi-Takoradi, Ghana (formerly the Gold Coast), from the late 19th century to the post-independence period. Focusing on the railway and port, the study implies that these projects were not merely technical symbols of modernity, but structural interventions that reorganised labour relations and society along capitalist lines, accelerating the formation of a wage-earning working class and the rise of trade unionism. The research demonstrates how British colonial capital systematically promoted new forms of wage-based labour relations in these infrastructure sectors, marginalising pre-existing tributary and kin-based economic modes of production. From this historical process emerged a new social bloc or class which began to organise politically. Indeed, the unionised labour movement of Sekondi-Takoradi played a crucial role in the anti-colonial struggles and, subsequently, represented a significant challenge to Kwame Nkrumah’s socialist state-driven development. The study also highlights the contradictions inherent in this specific labour history. Trade unions’ defence of the interests of what some have termed a local “labour aristocracy” contributed, on the one hand, to Nkrumah’s downfall and the consolidation of a neocolonial form of economic dependency; on the other hand, it led to the decline of the working class itself, whose trade union leadership failed to understand that the end of the socialist experiment would coincide with the dismantling of the very infrastructures that had created and sustained its members. This contribution fits into the global history of infrastructure from a labour history perspective, highlighting the decisive role of colonial capital in shaping African working-class formation and political-union dynamics in colonial and postcolonial Gold Coast/Ghana.