This chapter analyzes the emergence, the construction and the trajectory of road space reallocation as a policy solution to urban mobility challenges in different political contexts. Focusing on the notion of policy solution ownership (Gusfield, 1981) and drawing on extensive empirical work on sustainable urban mobility transitions in European cities, it contributes to the book’s main argument in three ways. First it examines how and by whom policy solution ownership is built and how it contributes to redefining the boundaries of a given problem in a highly competitive policy environment. Second, and following the work by Callon (1986) on problematization and interessement to account for improbable alliances in a highly fragmented policy context, it contributes to the understanding of how policy solution ownership opens new opportunities for urban elites to challenge existing urban governance arrangements and promote their own political agenda. Three, it discusses the role of framing in shaping the subsequent trajectory of this policy solution (Rochefort, Cobb, 1994) across different urban governance contexts. It argues that policy solution ownership was established through the continued efforts made by a coalition of policy entrepreneurs to transform a policy solution fitted for all seasons into an easily transferable set of standardized tools and techniques while at the same time shifting the attention away from car use reduction towards ensuring fair and equal access to the urban road network.