Equipping Participation Formats with Generative AI: A Case Study Predicting the Future of a Metropolitan City in the Year 2040

Urban planning is a complex field that requires the integration of diverse skills, knowledge, and perspectives. Engaging the public in this process promises to achieve high acceptance for resulting endeavors but poses significant challenges, particularly due to the varying levels of technical and artistic skills among participants. Moreover, discussions and collaborative efforts in urban planning often lack practical visualization tools, making it difficult to imagine and debate future urban scenarios. Generative Artificial Intelligence (GenAI) has emerged as a promising technology capable of bridging these gaps. GenAI can generate natural language output and visual content from textual descriptions, offering a novel way to facilitate more inclusive and productive participation in urban planning processes. In this paper, we explore the application of GenAI in a participatory urban planning event utilizing the novel Prompt-a-thon format. We conducted a study involving 64 participants who utilized GenAI in small groups to envision, design, and discuss the future urban landscape of the metropolitan city of Hamburg in Germany. Through this process, we examined the human-AI collaboration, assessing the technology's ability to accommodate varying skills and improve visualization in planning discussions. Our findings indicate that GenAI contributes to leveling diverse skill sets of participants, enabling more people to contribute insights into urban planning discussions. The technology also proved effective in overcoming visualization barriers, thus facilitating more engaging and fruitful discussions about future urban scenarios. These results underscore the potential of GenAI as a valuable tool in the evolving landscape of urban planning and public participation.