Public transport has long been analysed, modelled and planned as an engineered system for urban mobility, with limited consideration of its role as public space. However, from the perspective of individual users, a defining characteristic of public transport is the distinct form of public space it creates: riders have limited privacy and control over their surroundings, and space is often shared by diverse social groups (Mattioli, 2014, p. 58). The publicness of urban space is a multifaceted concept, relating to ownership, rights, access and citizenship (Loukaitou-Sideris & Ehrenfeucht, 2012, p. 8). As cities seek to reconfigure mobility systems to respond to climate change and improve quality of life, technocentric approaches focused on movement and efficiency cannot grapple with the emergent political challenges (Nikolaeva et al., 2019). Contestation often arises over attempts to reallocate urban street space away from private vehicles to sustainable transport modes or other activities (Keblowski et al., 2016). The motivations for, and different forms of opposition to planned transport improvements reveal conflicting perceptions of what is, or should be, public in urban areas. Across Europe, contestation of schemes to reallocate space to public transport, and the elevation of transport projects to electoral agendas, can undermine transitions to sustainable mobility. This paper presents an analysis of two European cities (London, Budapest), drawing from data collected through workshops and stakeholder interviews. Analysis of the discourses and tactical approaches used to contest street space re-allocation compares their diverse approaches, influenced by local socio-cultural norms. Furthermore, the analysis considers how local transport governance and organisational arrangements structure the relative influence of these norms for decision-making. Our findings advance the inquiry into public transport’s role in producing space, illustrating how institutional and governance arrangements structure the influence of socio-cultural norms on the publicness of public transport space.