From epistemic promises to real world practices: the ongoing becoming of 3D models and urban digital twins in municipal planning

The prominence of 3D city models and urban digital twins has expanded rapidly in both policy agendas and academic debates. Within urban planning, they have been promoted as transformative tools for climate adaptation, citizen engagement and data-driven decision-making. As early as in 2017, digital twins appeared among Gartner’s Top 10 technology trends, with expectations that the technology would reach mainstream adoption within a decade. Other forecasts suggested that by 2025, more than 500 cities worldwide would have developed and adopted an urban digital twin. Much research has therefore examined how digital twin initiatives have been launched and developed in large metropolitan cities. While this work has provided important insights into the visions, promises, and aspirations surrounding these technologies, often in the form of sociotechnical imaginaries, less attention has been paid to the actual practical challenges and complexities that municipal practitioners encounter when integrating them. To address this research gap, we examine how municipalities in Denmark and Sweden aspire to integrate 3D models and digital twins into their planning processes. Drawing on insights from participation in municipal pilot projects and 3D workshops, in conjunction with interviews with urban planners, architects, GIS employees and technology vendors, we examine how the promises of these technologies translate into everyday practices. In so doing, we highlight recurring practical challenges, including fragmented data infrastructures, discrepancies between national initiatives and local needs, limited organisational capacity, and competing interpretations of what these technologies should deliver. Finally, in the era of agentic AI and with the increasing usage of digital tools in urban planning, we contemplate how these technologies might interact with existing forms of legislation and decision-making when digital representations of cities begin to inform, support, or even challenge existing frameworks?