Commercial flows (deliveries to shops, restaurants, individual and business customers) supply urban areas and are so integrated to the way cities function that they become barely noticeable. They are often considered to be a source of road congestion and pollution. Yet, throughout the world, they are deemed necessary and grow continually and quickly. In this context, the issue of urban logistics (organization and distribution of trade flows in cities) is a recent and international research topic. However, few studies have dealt with urban logistics in the context of cities from the Global South despite the fact that their issues are similar to that of the Global North. By cross-analysing Brussels, Paris, Casablanca, and Nouakchott, we aim to document how logistics transitions, marked by various forms of dualisation are at stake in cities from both the Global North and the Global South. The aforementioned cities from the Global South will help us better understand the ongoing transformations in Paris and Brussels, such as the growth of opportunities and risks that is consubstantial to the atomization and fragmentation of logistics operations in the city core, and its outsourcing to small-scale carriers. Conversely, the case of European cities brings light to what is taking place in the Global South, that is, the structuring of major national and global operators' networks from hubs located mainly in semi-urban areas. In this changing urban logistics landscape, looking at both Northern and Southern cities shows that analogous transformations take place in many cities of the world. By entering into the day-to-day reality of this sector in these four metropolitan areas, we wish to highlight the challenges of social, economic and political sustainability in the context of the growth of trade flows in the world's major cities. The research method of the Trans-Log project is both hypothetico-deductive and inductive: it starts from strong hypotheses (about dualisation and a beginning of logistics transitions) and at the same time will proceed inductively thanks to the feedback from the four field studies. The research method is also multi-scalar: from the analysis of commercial districts, which will serve as a starting point for our field work, to the North-South macro-regional links (i.e. integrated into a transnational space), via the articulation of logistics circuits within the urban area. The project is organised around four tasks that combine spatial and territorial contextualisation of logistics and field work phases. A transversal action of valorisation and dissemination, aimed at stakeholders outside the academic community, completes this framework.