Abstract for: Tackling grand challenges: Evaluating causal loop diagrams as a boundary object in a transdisciplinary research project

Transdisciplinary research is essential for addressing grand challenges but often faces barriers related to communication, knowledge integration, and stakeholder collaboration. Managing large-scale transdisciplinary research projects requires structured approaches to facilitate problem structuring, decision-making, and knowledge co-production. This study examines the role of Causal Loop Diagrams (CLDs) as boundary objects in transdisciplinary project management, focusing on their effectiveness in fostering shared understanding, aligning research agendas, and enhancing interdisciplinary collaboration. This study employs a qualitative case study approach, using the CAMELLIA project—a six-year, £5 million transdisciplinary research initiative on urban water management in London—as an empirical context. The study examines how CLDs were used across different project phases to structure discussions, integrate diverse perspectives, and guide research and decision-making. A Theory of Change (ToC) framework is applied to assess the role of CLDs in shaping project outcomes. Findings indicate that CLDs supported problem structuring by mapping interdependencies and facilitating interdisciplinary dialogue. Participants found that CLDs enhanced shared understanding and helped track project evolution, making them effective tools for collaboration. However, challenges emerged, including conceptual disagreements, evolving stakeholder dynamics, and the need for continuous refinement. While CLDs helped visualise complexity, their simplification of systemic interactions occasionally led to difficulties in capturing dynamic project changes. The study highlights the potential of CLDs as boundary objects in transdisciplinary research project management. While they serve as effective tools for structuring discussions and fostering interdisciplinary collaboration, their use must be iterative and adaptive to address evolving challenges. Embedding CLDs within a structured Theory of Change framework can enhance their utility for project planning, implementation, and evaluation. Future research should explore how CLDs can be systematically institutionalised in transdisciplinary research to support long-term knowledge integration and decision-making.