Intermunicipal relationships have been singled out by the city of Antwerp as an instrumental arrangement to draft the RoutePlan 2030, but also as a specific governance challenge. This note (1) explores how and why European metropolitan agglomerations address the difficulties encountered in scaling up behavioural change at metropolitan level (e.g. lack of expertise, administrative organisation, participation of smaller municipalities to metropolitan projects, etc.); and (2) identifies main institutional, organisational and political barriers (fragmentation of views, excessive centralization of power at regional level, integration between sectors at metropolitan level). Focusing on the developments underway in Antwerp, the technical note on the various ways through which institutional rescaling shapes policymaking at the metropolitan level.