Large and complex construction projects are routinely late, over budget, under scope or any combination of the three. Academic literature identifies the area of conflicting stakeholder objectives, also called social complexity, as the most challenging and problem-prone aspect of complex construction projects. This view is also shared by the industry. This problem is addressed by the Open Design methodology. The latest addition to Open Design is the Preferendus, which is a system that allows to arrive at a group optimal project design by means of stakeholder preference optimization. Some applications of Preferendus result in stalemates, which can potentially lead to conflict escalation and have a destructive effect on the collaborative process they arose from. To address this, a Preferendus-based Python decision support system (DSS) is created that enables stalemate identification and resolution.

The developed DSS is applied onto the Duurzame Polder case, which is an ongoing sustainable energy generation project by the municipalities of Oss and ‘s-Hertogenbosch currently in the scope definition stage with public project information. The DSS is validated via two workshops with TU Delft Master students who take on the roles of the decision-makers in the project and use the DSS to identify and resolve the stalemate. The results indicate that the produced system successfully enables decision-makers to understand and discuss the reasons behind the stalemate to arrive at the final project decision. In both testing rounds the decision-makers arrived at a solution consistent with the real-world development of the project. The main limitations of this thesis are a lack of access to industry professionals, relative case modelling simplicity and the required model runtime. Recommendations for increasing the accuracy and efficiency of the produced system are provided.