This article discusses the interplay of urban transport infrastructures and their need to and of discipline. Drawing on participatory observation, ride-alongs, and interviews, it elaborates the case of BRT introduction in Dar es Salaam and illustrates how various humans and nonhumans needed to be disciplined so that the Dar es Salaam Rapid Transit system could become operational. Referring to the conceptualizations of mediating technologies (Latour, 1994) and disciplinary devices (Ureta, 2012), this article elaborates how the new transport system disciplines its environment, and how it is itself disciplined through different norms and materialities. However, discipline did not realize as planned. De-scriptions (Akrich, 1992) of the system’s disciplining technologies occurred, as practices turned out differently. New forms and effective combinations of established practices and changing structures have led to fluid formations of urban transport. Two perspectives enable to deeply understand this transitional process. First, a sociotechnical perspective shows how agency has been (re)distributed and mediated through technologies and artefacts that were implemented to secure smooth bus operations. Second, a historical perspective elucidates how previous and prevalent practices of Tanzania’s minibus system and other road users impacted the formation of DART. The article hence demonstrates that technological innovation and spatial reorganization do not only lead to new forms of discipline, but to ongoing mediations and negotiations of transport practices.