A pilot mobile application enhanced by augmented reality to support participatory CoDesign in shared public spaces

Public spaces are critical urban infrastructure, shaping everyday experiences and supporting sociocultural life. Public participation has long underpinned the planning, maintenance, and redesign of these spaces, yet most digital tools remain limited to conceptual experiments based on brief engagement rather than active participatory processes with sustained feedback loops for maintenance and incremental improvement in the long-term. In this research, we present CoDesign, a cross-platform mobile application that couples user-centered design with map-based reporting and augmented reality (AR) visualization to facilitate anywhere-anytime participation. Building on established conceptual frameworks, CoDesign supports geotagged reports with multimodal inputs and collaborative 3D design suggestions through AR. To test effectiveness, we conducted two rounds of moderated usability testing in five U.S. cities to assess reporting workflows and AR-assisted interactions. The results indicate that geotagged survey flow is straightforward and widely accessible, whereas AR features stimulate creative engagement but also expose limitations in the user interaction experience. In addition, CoDesign can mitigate time and place constraints, with the potential to support a more immersive and context-aware participatory experience. Looking ahead, future participatory platforms must strike a balance between usability and technological novelty to enhance both the processes and the quality of participation.