The cities of Africa and Asia are projected to account for 80 % of the future urban growth. Challenges brought forward by motorization and lack of accessibility; urban streets take a central position in the discussion of the sustainable city. This offers a considerable challenge in shaping cities while addressing climate change. Meanwhile there is lack of theorizations stemming from global South research. Planning models used for street planning comes from contexts far removed from the urban realities of the South. Sub-Saharan Africa has relatively low road network densities while experiencing a strong urban growth. The object of the study is Addis Ababa, a future megacity where street development is one of the central topics in the city’s planning.This thesis investigates the rationalities expressed by experts around street planning in Addis Ababa and how that shapes the planning discourse in the city. Methods employed are semi- structured interviews, desktop study and participant observations. The study uses conceptual tools from a wide range of literature on rationalities, research in the global South, extraversion, acting and action space of professionals.The results show how rationalities expressed can be understood as four rationality groupings 1) rationalities expressed regarding visions of the city, 2) rationalities expressed regarding the functions of streets, 3) rationalities expressed how to process a project and 4) rationalities expressed regarding relationship and power dynamics. Through the interplay between the rationality groupings a perceived space of action emerges. The rationalities influence what actors see as possible and desirable courses of action. The study concludes that all rationality groupings are not equal, instead visions of the city and relational rationalities seem to hold larger influence on shaping the streetscapes of Addis Ababa. Further, less rigid formulations of what constitutes the formal action space, allows third sector actors to influence and diffuse their rationalities into the city’s street planning process.