This paper aims at evaluating how deepening the study of the chaîne opératoire might help in understanding the layout of Roman urban workshops. This concept, initially developed by A. Leroi-Gourhan, is generally presented as a mere sequence of operations that would follow raw material in its transformation into final product. Most presentations do not take into account the variability of such paths or do not properly distinguish crucial steps from optional ones. By taking into account the localization of all observed steps after their characterization, it is possible to proceed to a detailed analysis of the workshops layouts, their variations and interpret the latter both in technical and economic terms. Despite the many insights such a method might bring, it remains difficult to apply on certain crafts, such as glass or metal secondary production which are centred on the furnace and for which the main operations cannot be reconstructed without other tools, scraps or final products.